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Influence of Cement Replacement with Sewage Sludge Ash (SSA) on the Heat of Hydration of Cement Mortar
- Elżbieta Haustein
- Aleksandra Kuryłowicz-Cudowska
- Aneta Łuczkiewicz
- Sylwia Fudala-Książek
- Bartłomiej Cieślik
2022 Pełny tekst Materials
The amount of fly ash from the incineration of sewage sludge is increasing all over the world, and its utilization is becoming a serious environmental problem. In the study, a type of sewage sludge ash (SSA) collected directly from the municipal sewage treatment plant was used. Five levels of cement replacement (2.5%, 5%, 7.5%, 10% and 20%) and unchanged water-to-binder (w/b) ratio (0.55) were used. The purpose of the study was to evaluate the effect of sewage sludge ash (SSA) on the hydration heat process of cement mortars. The heat of the hydration of cement mortars was monitored by the isothermal calorimetric method for 7 days at 23 °C. The analysis of chemical composition and particle size distribution was performed on the tested material. The tests carried out have shown that SSA particles have irregular grain morphology and, taking into account the chemical composition consists mainly of oxides such as CaO, P2O5, SiO2 and Al2O3. The concentration of these compounds affects the hydration process of cement mortars doped with SSA. In turn, the content of selected heavy metals in the tested ash should not pose a threat to the environment. Calorimetric studies proved that the hydration process is influenced by the presence of SSA in cement mortars. The studies showed that the rate of heat generation decreased (especially in the initial setting period) with the increasing replacement of cement by SSA, which also reduced the amount of total heat compared to the control cement mortar. With increasing mass of the replacement of cement with SSA up to 20%, the 7-day compressive strength of the mortar samples decreases.
Influence of Different Nanometals Implemented in PMMA Bone Cement on Biological and Mechanical Properties
- Beata Świeczko-Żurek
- Andrzej Zieliński
- Dorota Bociąga
- Karolina Rosińska
- Grzegorz Gajowiec
2022 Pełny tekst Nanomaterials
Cemented arthroplasty is a common process to fix prostheses when a patient becomes older and his/her bone quality deteriorates. The applied cements are biocompatible, can transfer loads, and dampen vibrations, but do not provide antibacterial protection. The present work is aimed at the development of cement with antibacterial effectivity achieved with the implementation of nanoparticles of different metals. The powders of Ag, Cu with particles size in a range of 10–30 nm (Cu10) and 70–100 nm (Cu70), AgCu, and Ni were added to PMMA cement. Their influence on compression strength, wettability, and antibacterial properties of cement was assessed. The surface topography of samples was examined with biological and scanning electron microscopy. The mechanical properties were determined by compression tests. A contact angle was observed with a goniometer. The biological tests included an assessment of cytotoxicity (XTT test on human cells Saos-2 line) and bacteria viability exposure (6 months). The cements with Ag and Cu nanopowders were free of bacteria. For AgCu and Ni nanoparticles, the bacterial solution became denser over time and, after 6 months, the bacteria clustered into conglomerates, creating a biofilm. All metal powders in their native form in direct contact reduce the number of eukaryotic cells. Cell viability is the least limited by Ag and Cu particles of smaller size. All samples demonstrated hydrophobic nature in the wettability test. The mechanical strength was not significantly affected by the additions of metal powders. The nanometal particles incorporated in PMMA-based bone cement can introduce long-term resistance against bacteria, not resulting in any serious deterioration of compression strength.
Influence of Fluid Compressibility and Movements of the Swash Plate Axis of Rotation on the Volumetric Efficiency of Axial Piston Pumps
- Paweł Załuski
2022 Pełny tekst ENERGIES
This paper describes the design of a swash plate axial piston pump and the theoretical models describing the bulk modulus of aerated and non-aerated fluids. The dead space volume is defined and the influence of this volume and the fluid compressibility on the volumetric efficiency of the pump is considered. A displacement of the swash plate rotation axis is proposed to reduce the dead space volume for small swash plate swing angles. A prototype design of a pump with a displaced axis of rotation of a swash plate with two directions of delivery is presented, in which the capacity is changed by means of a valve follow-up mechanism. Comparative results for a pump with a displaced and a non-displaced swash plate rotation axis are presented, which confirm that displacement of the swash plate rotation axis causes an increase in volumetric efficiency that is apparent for high pressure discharge and small swash plate angles. The determined characteristics were compared with a mathematical model taking into account the compressibility of the fluid in the dead space volume and a satisfactory consistency was obtained.
Influence of Heat Treatment Temperature on Fatigue Toughness in Medium-Carbon High-Strength Steels
- G. Wheatley
- Ricardo Branco
- José A. F. O. Correia
- Rui F. Martins
- Wojciech Macek
- Zbigniew Marciniak
- M. Szala
2022 Pełny tekst Structural Integrity
Current research has demonstrated that the tempering temperature affects the martensitic transformation of medium-carbon high-strength steels. This temperature plays an important role in the final microstructure, percentage ratios of martensite to ferrite phases and, consequently, in the mechanical properties and the fatigue response. So far, the relationship between the martensitic tempering temperature and the cyclic deformation properties is not clearly understood. Moreover, the effect of the martensitic tempering temperature on fatigue toughness has not been studied yet. Therefore, this paper aims to study, in a systematic manner, the fatigue toughness of medium-carbon high-strength steels heat treated at different temperatures under fully reversed strain-controlled conditions.
Influence of Laser Modification on the Surface Character of Biomaterials: Titanium and Its Alloys—A Review
- Joanna Sypniewska
- Marek Szkodo
2022 Pełny tekst Coatings
Laser surface modification is a widely available and simple technique that can be applied to different types of materials. It has been shown that by using a laser heat source, reproducible surfaces can be obtained, which is particularly important when developing materials for medical applications. The laser modification of titanium and its alloys is advantageous due to the possibility of controlling selected parameters and properties of the material, which offers the prospect of obtaining a material with the characteristics required for biomedical applications. This paper analyzes the effect of laser modification without material growth on titanium and its alloys. It addresses issues related to the surface roughness parameters, wettability, and corrosion resistance, and discusses how laser modification changes the hardness and wear resistance of materials. A thorough review of the literature on the subject provides a basis for the scientific community to develop further experiments based on the already investigated relationships between the effects of the laser beam and the surface at the macro, micro, and nano level.
Influence of Material Thickness on the Ductile Fracture of Steel Plates for Shipbuilding
- Jakub Kowalski
- Janusz Kozak
2022 Pełny tekst Polish Maritime Research
In the shipbuilding industry, the risk of brittle fractures is relatively high because some units operate in arctic or subarcticzones and use high thickness (up to 100 mm) steel plates in their structures. This risk is limited by employing certifiedmaterials with a specific impact strength, determined using the Charpy method (for a given design temperature) and byexercising control over the welding processes (technology qualification, production supervision, and non-destructive tests).However, for offshore constructions, such requirements may prove insufficient. For this reason, regulations employed inconstructing offshore structures require conducting crack tip opening displacement (CTOD) tests for steel and weldedjoints with thicknesses exceeding 40 mm for high tensile strength steel and 50 mm for other steel types. Since classificationcodes do not accept the results of CTOD tests conducted on specimens of sub-sized dimensions, the problem of theoreticallymodelling the steel construction destruction process is of key importance, as laboratory tests for notched elements ofconsiderable thickness (100 mm and higher) are costly and problems stemming from high loads and a wide range ofrecorded parameters are not uncommon. The aim of this research is to find a relationship between material thickness andCTOD value, by establishing and verifying a numerical model that allows recalculating a result obtained on a sub-sizespecimen to a full- size specimen for a ductile fracture mode. This work presents results and conclusions from numericalmodelling and compares them with laboratory test results of the elastic-plastic properties of high thickness steel, typicallyused in offshore applications.
Influence of PWHT Parameters on the Mechanical Properties and Microstructural Behavior of Multi-Pass GTAW Joints of P92 Steel
- Sachin Sirohi
- Amit Kumar
- Shiva Soni
- Gaurav Dak
- Sanjeev Kumar
- Aleksandra Świerczyńska
- Grzegorz Rogalski
- Dariusz Fydrych
- Chandan Pandey
2022 Pełny tekst Materials
The 9% Cr steels were developed for ultra-supercritical (USC) power plants to meet the requirements of high operating temperature and pressure. These steels are produced to operate at high temperatures where impact toughness is not a concern; however, it becomes important for the welded joints to have good impact toughness at room temperature for manufacturing. The present work investigates the effect of the post-weld heat treatment (PWHT) parameters, i.e., temperature and time, on the impact toughness of multi-pass gas tungsten arc welded (GTAW) joints of ferritic/martensitic grade P92 steel. The microstructural evolution in welded joints given varying post-weld temperatures and times was studied. The lath martensitic structure of the weld metal for the as-welded joints resulted in high hardness and low impact toughness. The weld fusion zone toughness was 12 J, which was lower than the minimum specified values of 41 J (ASME standards) and 47 J (EN ISO 3580:2017). The PWHT temperature and time were found to have a significant effect on the impact toughness of the weld metal. A drastic increase in the impact toughness of the weld metal was noticed, which was attributed to lath break-up, reduction in dislocation density and reduction in solid solution hardening. The maximum impact toughness of 124 J was measured for PWHT temperature and time of 760 C and 120 min, respectively. The effect of PWHT parameters on tensile strength was also investigated, and test results showed that the joint was safe for USC boiler application as it failed from the region of the P92 base metal. The variation in microstructural evolution along the weldments resulted in hardness variation. PWHT led to homogeneity in microstructure and, ultimately, reduction in hardness value. According to the study, the optimum temperature and time for PWHT of a GTAW joint of P92 steel were found to be 760 C and 120 min, respectively.
Influence of Rock Dust Additives as Fine Aggregate Replacement on Properties of Cement Composites—A Review
- Magdalena Dobiszewska
- Orlando Bagcal
- Ahmet Beycioğlu
- Dimitrios Goulias
- Fuat Köksal
- Maciej Niedostatkiewicz
- Hüsamettin Ürünveren
2022 Pełny tekst Materials
Concrete production consumes enormous amounts of fossil fuels, raw materials, and is energy intensive. Therefore, scientific research is being conducted worldwide regarding the possibility of using by-products in the production of concrete. The objective is not only to identify substitutes for cement clinker, but also to identify materials that can be used as aggregate in mortar and concrete productions. Among the potential alternative materials that can be used in cement composite production is rock dust of different geological origin. However, some adversarial effects may be encountered when using rock dust regarding the properties and durability of mortars and concrete. Therefore, comprehensive research is needed to evaluate the adequacy of rock dust use in cementitious composite production. This paper presents a comprehensive review of the scientific findings from past studies concerning the use of various geological origins of rock dust in the production of mortars and concrete. The influence of rock dust as a replacement of fine aggregates on cementitious composites was analyzed and evaluated. In this assessment and review, fresh concrete and mortar properties, i.e., workability, segregation, and bleeding, mechanical properties, and the durability of hardened concrete and mortar were considered.
Influence of stabilizing osmolytes on hen egg white lysozyme fibrillation
- Jarosław Wawer
- Emilia Kaczkowska
- Jakub Karczewski
- Danuta Augustin-Nowacka
- Joanna Krakowiak
2022 JOURNAL OF BIOMOLECULAR STRUCTURE & DYNAMICS
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Influence of Surface Modification of Titanium and Its Alloys for Medical Implants on Their Corrosion Behavior
- Łukasz Pawłowski
- Magda Rościszewska
- Majkowska-marzec Beata
- Magdalena Jażdżewska
- Michał Bartmański
- Andrzej Zieliński
- Natalia Tybuszewska
- Pamela Samsel
2022 Pełny tekst Materials
Titanium and its alloys are often used for long-term implants after their surface treatment. Such surface modification is usually performed to improve biological properties but seldom to increase corrosion resistance. This paper presents research results performed on such metallic materials modified by a variety of techniques: direct voltage anodic oxidation in the presence of fluorides, micro-arc oxidation (MAO), pulse laser treatment, deposition of chitosan, biodegradable Eudragit 100 and poly(4-vinylpyridine (P4VP), carbon nanotubes, nanoparticles of TiO2, and chitosan with Pt (nano Pt) and polymeric dispersant. The open circuit potential, corrosion current density, and potential values were determined by potentiodynamic technique, and microstructures of the surface layers and coatings were characterized by scanning electron microscopy. The results show that despite the applied modifications, the corrosion current density still appears in the region of very low values of some nA/cm2. However, almost all surface modifications, designed principally for the improvement of biological properties, negatively influence corrosion resistance. The reasons for observed effects can vary, such as imperfections and permeability of some coatings or accelerated degradation of biodegradable deposits in simulated body fluids during electrochemical testing. Despite that, all coatings can be accepted for biological applications, and such corrosion testing results are presumed not to be of major importance for their applications in medicine.
Influence of the Shear Cap Size and Stiffness on the Distribution of Shear Forces in Flat Slabs
- Maciej Grabski
- Andrzej Ambroziak
2022 Pełny tekst Materials
The scope of this paper is to investigate analytically and numerically the influence of shear cap size and stiffness on the distribution of shear forces in flat slabs in a slab–column-connections-reinforced concrete structure. The effect of support (shear cap) stiffness on the calculation of the length of the shear control perimeter according to the available methods is presented. Based on the analysis, the authors indicate in what range of support stiffness the corner concentrations become important in the calculation of the punching resistance. For shear caps with high flexibility (≤ 0.5), the concentration of internal forces in the corners does not occur. The authors compare the numerical results obtained from the calculation methods and indicate the correlations, which can be useful guidance for structural designers. In the case of large shear caps, the simplified MC2010 method gives a significantly lower value of the effective control perimeter length compared to more accurate methods. This paper is intended to provide scientists, civil engineers, and designers with guidelines on which factors influence punching shear load capacity of the slab–column connections with shear caps.
Influence of the Tool Rotational Speed on Physical and Chemical Properties of Dissimilar Friction-Stir-Welded AA5083/AA6060 Joints
- Aleksandra Laska
- Marek Szkodo
- Pasquale Cavaliere
- Angelo Perrone
2022 Pełny tekst Metals
Aluminum alloys have been successfully used in the railroad and automotive industries because of their potential to significantly reduce component weights, and their good mechanical and anti-corrosion properties. Problems with joining aluminum alloys are characterized by low weldability, which influences the need for studies focused on unconventional methods. The environmentally friendly and low-cost friction-stir-welding method enables the material to be joined without melting. In the following study, dissimilar butt joints were produced from AA5083 and AA6060 alloys. A constant tool traverse speed of 100 mm/min and a tool tilt angle of 2º were used, combined with tool rotational speeds of 800, 1000 and 1200 RPM. It was revealed that as the tool speed increases, the hardness in the weld nugget zone increases, due to higher heat input and more effective recrystallization. The highest hardness of the mweld nugget zone was observed for the weld that was produced with the highest tool rotational speed, and was equal to 1.07 GPa, compared to the hardness of both parent materials of 0.75 and 1.15 GPa for AA5083 and AA6060, respectively. mIncreasing the heat input also decreased the hardness of the heat-affected zone, where recrystallization was not bobserved. The lowest density of dislocations with the highest mobility was observed in the heat-affected zone on the AA6060 side, which also contributed to the reduction in strength in this zone. The produced welds exhibited corrosion resistance between both parent materials, with the lowest corrosion current density being 6.935 ± 0.199 µA·cm–2 for the weld that was produced at a tool speed of 1200 RPM.
Influence of Urea and Dimethyl Sulfoxide on K-Peptide Fibrillation
- Jarosław Wawer
- Jakub Karczewski
- Robert Aranowski
- Rafał Piątek
- Danuta Augustin-Nowacka
- Piotr Bruździak
2022 Pełny tekst INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
Protein fibrillation leads to formation of amyloids—linear aggregates that are hallmarks of many serious diseases, including Alzheimer’s and Parkinson’s diseases. In this work, we investigate the fibrillation of a short peptide (K-peptide) from the amyloidogenic core of hen egg white lysozyme in the presence of dimethyl sulfoxide or urea. During the studies, a variety of spectroscopic methods were used: fluorescence spectroscopy and the Thioflavin T assay, circular dichroism, Fourier-transform infrared spectroscopy, optical density measurements, dynamic light scattering and intrinsic fluorescence. Additionally, the presence of amyloids was confirmed by atomic force microscopy. The obtained results show that the K-peptide is highly prone to form fibrillar aggregates. The measurements also confirm the weak impact of dimethyl sulfoxide on peptide fibrillation and distinct influence of urea. We believe that the K-peptide has higher amyloidogenic propensity than the whole protein, i.e., hen egg white lysozyme, most likely due to the lack of the first step of amyloidogenesis—partial unfolding of the native structure. Urea influences the second step of K-peptide amyloidogenesis, i.e., folding into amyloids.
Influence of User Mobility and Antenna Placement on System Loss in B2B Networks
- Manuel M. Ferreira
- Filipe D. Cardoso
- Sławomir Ambroziak
- Luis M. Correia
2022 Pełny tekst IEEE Access
In this paper, the influence of user mobility and on-body antenna placement on system loss in body-to-body communications in indoor and outdoor environments and different mobility scenarios is studied, based on system loss measurements at 2.45 GHz. The novelty of this work lies on the proposal of a classification model to characterise the effect of user mobility and path visibility on system loss, allowing to identify the best set of on-body antenna placements. To quantify the influence of visibility and mobility on the average system loss, a combined score is proposed, allowing to map system loss onto the degree of visibility and mobility that depends on the scenario being considered and on on-body antenna placements. Overall, a good agreement is observed between the proposed classification model and the average measured values of system loss, with the higher values of combined scores being associated with lower values of systems loss. For the cases under study, the average values of system loss are 61.6 dB for the cases of the antennas being positioned only on the front of the body and/or the head, and 64.5 dB if at least one of the antennas is placed on an arm.
Influence of Water-Induced Degradation of Polytetrafluoroethylene (PTFE)-Coated Woven Fabrics Mechanical Properties
- Andrzej Ambroziak
- Paweł Kłosowski
2022 Pełny tekst Materials
The impact of water-induced degradation on the mechanical properties of the chosen two PTFE-coated, glass threads woven fabrics is investigated in this paper. The paper begins with a survey of literature concerning the investigation and determination of coated woven fabric properties. The authors carried out the uniaxial tensile tests with an application of flat and curved grips to establish the proper values of the ultimate tensile strength and the longitudinal stiffness of groups of specimens treated with different moisture conditions. Despite the water resistance of the main materials used for fabrics manufacturing, the change of the mechanical properties caused by the influence of water immersion has been noticed. The reduction in the tensile strength resulting under waterlogged is observed in the range from 5% to 16% depending on the type of investigated coated woven fabric and direction of weft or warp.
Inhibitive effect of sodium molybdate on corrosion of AZ31 magnesium alloy in chloride solutions
- Maria Osipenko
- Dmitry Kharitonov
- Aliaksandr Kasach
- Jacek Ryl
- Janusz Adamiec
- Irina Kurilo
2022 ELECTROCHIMICA ACTA
In this work, corrosion inhibition of the AZ31 magnesium alloy was investigated in NaCl solutions containing different amounts of sodium molybdate inhibitor. Electrochemical, hydrogen evolution, microscopic, and spectroscopic experiments were utilized to examine the mechanism of corrosion inhibition by molybdates. The results showed that Na2MoO4 inhibitor provides reliable inhibition at high concentrations (150 mM). Surface examination by Raman and XPS spectroscopy confirmed the formation of a protective surface layer of mixed Mo(VI, V, IV) species. Based on these results, the mechanism of corrosion inhibition of the AZ31 alloy by aqueous molybdates was proposed.
Inhibitors of glucosamine-6-phosphate synthase as potential antimicrobials or antidiabetics – synthesis and properties
- Joanna Stefaniak
- Michał Nowak
- Marek Wojciechowski
- Sławomir Milewski
- Andrzej Skwarecki
2022 Pełny tekst JOURNAL OF ENZYME INHIBITION AND MEDICINAL CHEMISTRY
Glucosamine-6-phosphate synthase (GlcN-6-P synthase) is known as a promising target for antimicrobial agents and antidiabetics. Several compounds of natural or synthetic origin have been identified as inhibitors of this enzyme. This set comprises highly selective L-glutamine, amino sugar phosphate or transition state intermediate cis-enolamine analogues. Relatively low antimicrobial activity of these inhibitors, poorly penetrating microbial cell membranes, has been improved using the pro-drug approach. On the other hand, a number of heterocyclic and polycyclic compounds demonstrating antimicrobial activity have been presented as putative inhibitors of the enzyme, based on the results of molecular docking to GlcN-6-P synthase matrix. The most active compounds of this group could be considered promising leads for development of novel antimicrobial drugs or antidiabetics, provided their selective toxicity is confirmed.
Inline Microstrip Bandpass Filter With Two Transmission Zeros and Increased Order Using Spurious Resonance of Frequency-Dependent Inverter
- Maciej Jasiński
- Muhammad Yameen Sandhu
- Adam Lamęcki
- Roberto Gómez-García
- Michał Mrozowski
2022 Pełny tekst
A design method for a class of fourth-order inline microstrip bandpass filter with two transmission zeros and 20% fractional bandwidth is presented. The filter consists of two quarter-wavelength transmission-line resonators coupled by a frequency-dependent inverter. The inverter is composed of two open-ended stubs that are connected by an interdigital capacitor and introduces two poles and two transmission zeros in the filter response. One of these poles is obtained from the spurious resonance of the capacitor, which leads to a very compact filter structure. An equivalent circuit model of the frequencydependent inverter is provided along with a detailed couplingmatrix-based synthesis procedure to design the filter prototype. The design theory is validated with a constructed 2-GHz proofof-concept prototype. Measured results are in close agreement with the synthesis and EM-simulated ones, hence verifying the devised design approach.
Inline Microwave Filters With N+1 Transmission Zeros Generated by Frequency-Variant Couplings: Coupling-Matrix-Based Synthesis and Design
- Martyna Mul
- Maciej Jasiński
- Adam Lamęcki
- Roberto Gómez-García
- Michał Mrozowski
2022 Pełny tekst IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS
A general coupling-matrix-based synthesis methodology for inline Nth-order microwave bandpass filters (BPFs) with frequency-variant reactive-type couplings that generate N+1 transmission zeros (TZs) is presented in this brief. The proposed approach exploits the formulation of the synthesis problem as three inverse nonlinear eigenvalue problems (INEVPs) so that the coupling matrix is built from their sets of eigenvalues. For this purpose, an optimization nonlinear least-squares procedure is employed. The theoretical foundations of the engineered INEVP coupling-matrix-based synthesis framework are described. In addition, its effectiveness is verified through various synthesis examples of a third-order BPF with four TZs based on different circuit models. Moreover, as experimental validation, a 2.4-GHz microstrip prototype of the distributed-element BPF synthesis example is built and measured.
Innovative Bidirectional Isolated High-Power Density On-Board Charge for Vehicle-to-Grid
- Roman Hrbáč
- Libor Hrdina
- Vaclav Kolar
- Zdenek Slanina
- Vojtech Blazek
- Tomas Vantuch
- Mikołaj Bartłomiejczyk
- Stanislav Misak
2022 Pełny tekst SENSORS
This paper deals with developing and implementing a bidirectional galvanically isolated on-board charger of a high-power density. The power density of the new charger was 4 kW/kg and 2.46 kW/dm3, and the maximum efficiency was 96.4% at 3.4 kW. Due to the requirement to achieve a high-power density, a single-stage inverter topology was used. Regarding switching losses, due to the topology of the circuit with so-called hard switching, the switching frequency was set to 150 kHz. A laboratory prototype was built to verify the properties and operating principles of the described charger topology. The on-board charger has been tested in a microgrid test platform. Due to the parasitic properties of the transformer and other electronic components, overvoltage with subsequent oscillations occurred on the primary side of the transformer and damped resonance on its secondary side. These parasitic properties caused interference and especially voltage stress on the semiconductor elements. These undesirable phenomena have been eliminated by adding an active element to the charger topology and a new transistor control strategy. This new switching control strategy of transistors has been patented.