Lublin University of Technology

Plasma-liquid interactions represent a growing interdisciplinary area of research involving plasma science, fluid dynamics, heat and mass transfer, photolysis, multiphase chemistry and aerosol science. This review provides an assessment of the state-of-the-art of this multidisciplinary area and identifies the key research challenges. The developments in diagnostics, modeling and further extensions of cross section and reaction rate databases that are necessary to address these challenges are discussed. The review focusses on non-equilibrium plasmas.

Rare earth elements (REE) have been recognised as critical raw materials, crucial for many clean technologies. As the gap between their global demand and supply increases, the search for their alternative resources becomes more and more important, especially for the countries which depend highly on their import. Coal fly ash (CFA), which when not utilised is considered waste, has been regarded as the possible source of many elements, including REE. Due to the increase in the energy demand, CFA production is expected to grow, making research into the use of this material a necessity. As Poland is the second biggest coal consumer in the European Union, the authors have studied different coal fly ashes from ten Polish power plants for their rare earth element content. All the fly ashes have a broadly similar distribution of rear earth elements, with light REE being dominant. Most of the samples have REE content relatively high and according to Seredin and Dai (Int J Coal Geol 94: 67-93, 2012) classification can be considered promising REE raw materials.

A common energy harvesting device uses a piezoelectric patch on a cantilever beam with a tip mass. The usual configuration exploits the linear resonance of the system; this works well for harmonic excitation and when the natural frequency is accurately tuned to the excitation frequency. A new configuration is proposed, consisting of a cantilever beam with a tip mass that is mounted vertically and excited in the transverse direction at its base. This device is highly non-linear with two potential wells for large tip masses, when the beam is buckled. The system dynamics may include multiple solutions and jumps between the potential wells, and these are exploited in the harvesting device. The electromechanical equations of motion for this system are developed, and its response for a range of parameters is investigated using phase portraits and bifurcation diagrams. The model is validated using an experimental device with three different tip masses, representing three interesting cases: a linear system; a low natural frequency, non-buckled beam; and a buckled beam. The most practical configuration seems to be the pre-buckled case, where the proposed system has a low natural frequency, a high level of harvested power and an increased bandwidth over a linear harvester.

The purpose of this paper is to discuss the different generations of photovoltaic cells and current research directions focusing on their development and manufacturing technologies. The introduction describes the importance of photovoltaics in the context of environmental protection, as well as the elimination of fossil sources. It then focuses on presenting the known generations of photovoltaic cells to date, mainly in terms of the achievable solar-to-electric conversion efficiencies, as well as the technology for their manufacture. In particular, the third generation of photovoltaic cells and recent trends in its field, including multi-junction cells and cells with intermediate energy levels in the forbidden band of silicon, are discussed. We also present the latest developments in photovoltaic cell manufacturing technology, using the fourth-generation graphene-based photovoltaic cells as an example. An extensive review of the world literature led us to the conclusion that, despite the appearance of newer types of photovoltaic cells, silicon cells still have the largest market share, and research into ways to improve their efficiency is still relevant.

This letter considers a nonlinear piezomagnetoelastic energy harvester driven by stationary Gaussian white noise. The increase in the energy generated by this device has been demonstrated for harmonic excitation with slowly varying frequency in simulation and validated by experiment. This paper considers the simulated response of this validated model to random base excitation and shows that the system exhibits a stochastic resonance. If the variance of the excitation were known then the device may be optimized to maximize the power harvested, even under random excitation.

Plastic-based materials are frequently used in packaging and can be seen universally in both the developed and developing societies. At present, most of the currently used food packaging materials are nondegradable and are creating serious environmental problems. New technologies are being explored and developed to study the complex interaction between the food packaging materials and food. For example, nanocomposite of cellulose constitutes environmentally friendly packaging, which is easily recycled by combustion and requires low power consumption in production. There are several such biodegradable materials which are available at a low price, have good mechanical properties and allow disposal in the soil. This is advantageous because biological degradation produces only carbon dioxide, water, and inorganic compounds to name a few. It has also been discovered that biodegradable plastics made of such materials can be disposed of together with organic waste. The widespread use of biopolymers in the place of standard plastics would help to reduce the weight of waste. Therefore, biodegradable materials take part in the natural cycle “from nature to nature” and play an important role for environmental sustainability. So, in this article, we briefly summarize the different characteristic of biodegradable polymers being used in food packaging applications.

Titanium and its alloys are commonly used in almost all disciplines of medicine because of their sufficient biocompatibility and meeting of mechanical requirements. However, dense metallic biomaterials represent only an interfacial connection with host tissue, may develop stress shielding which causes ingrowth of the fibrous tissue, and are prone to microbial adhesion and development of biomaterial associated infections. Therefore, development of a new, porous titanium biomaterial is proposed to improve an implant's interconnection with bone, provide better stabilization, and reduce the risk of the loss of the implant. In this review, recent findings in porous titanium biomaterials engineering are discussed, including the structural and strengthening aspects of titanium alloys. The porosity and design of porous structures, as well as the optimization process are also described. An extensive part of this section is dedicated to manufacturing processes. The next section of the review is devoted to osseointegration of porous implants and surface treatment processes, whose purpose are antibacterial activity or local drug delivery. Summarizing the article, some future predictions have been presented.

Conservation of cultural heritage is nowadays a very important aspect of our lives. Thanks to such legacy we gain knowledge about our ancestors, methods of production and ways of their life. The rapid development of 3D technology allows for more and more faithful reflection of this area of life. The rich cultural heritage, both tangible and intangible, can be preserved for future generations due to the use of advanced 3d technologies. They provide the means of documenting, recovering and presenting items of cultural heritage. Not only buildings or monuments are taken into account. An important aspect of our culture is intangible cultural heritage (ICH), including acting, crafting or storytelling, passed down from generation to generation. Due to the rapid development of civilisation and the migration of people, this type of culture is often forgotten. That is why the preservation of ICH is an important element of today world. The main aim of this study, on the basis of the gathered papers, is to identify: (1) the general state of use of 3D digital technologies in ICH; (2) the topics and themes discussed; (3) the technologies used in the study; (4) locations of research centres conducting such studies; and (5) the types of research carried out. The methodology consists of the following main steps: defining study questions, searching query development, selection of publications in Scopus, Web of Knowledge and IEEE Xplore, finally the study execution and the analysis of the obtained results. The results show that for ICH the most often used technologies are: 3D visualisation, 3D modelling, Augmented Reality, Virtual Reality and motion capture systems.

Cracks and cavities belong to two basic forms of damage to the concrete structure, which may reduce the load-bearing capacity and tightness of the structure and lead to failures and catastrophes in construction structures. Excessive and uncontrolled cracking of the structural element may cause both corrosion and weakening of the adhesion of the reinforcement present in it. Moreover, cracking in the structure negatively affects its aesthetics and in extreme cases may cause discomfort to people staying in such a building. Therefore, the following article provides an in-depth review of issues related to the formation and development of damage and cracking in the structure of concrete composites. It focuses on the causes of crack initiation and characterizes their basic types. An overview of the most commonly used methods for detecting and analyzing the shape of microcracks and diagnosing the trajectory of their propagation is also presented. The types of cracks occurring in concrete composites can be divided according to eight specific criteria. In reinforced concrete elements, macrocracks depend on the type of prevailing loads, whereas microcracks are correlated with their specific case. The analyses conducted show that microcracks are usually rectilinear in shape in tensioned elements; in shear elements there are wing microcracks with straight wings; and torsional stresses cause changes in wing microcrack morphology in that the tips of the wings are twisted. It should be noted that the subject matter of microcracks and cracks in concrete and structures made of this material is important in many respects as it concerns, in a holistic approach, the durability of buildings, the safety of people staying in the buildings, and costs related to possible repairs to damaged structural elements. Therefore, this problem should be further investigated in the field of evaluation of the cracking and fracture processes, both in concrete composites and reinforced concrete structures.

Abstract The objective of this study is to investigate the possibility of enhancing mechanical properties of poly(lactic acid) (PLA) samples processed by a rapid manufacturing (RM) technique by increasing PLA crystallinity degree via thermal annealing. The samples are manufactured by fused deposition modeling (FDM) at different temperatures and subsequently evaluated by three‐point bending flexural and tensile tests. The polymer processed at 215 °C is thermally annealed over its glass transition temperature in order to increase the degree of crystallinity to the maximum attainable level as measured by the differential scanning calorimetry and confirmed by X‐ray diffraction. The increase in the degree of crystallinity of FDM‐PLA enhances flexural stress of the samples by 11–17%. The study also demonstrates applicability of radiation sterilization for FDM‐PLA parts. Therefore, thermal annealing might be introduced into a standard RM technology of PLA, particularly for sterilizable customized implants, to efficiently improve their mechanical properties.

In this paper, we present the possibility of using fly ash to produce synthetic zeolites. The synthesis class F fly ash from the Stalowa Wola SA heat and power plant was subjected to 24 h hydrothermal reaction with sodium hydroxide. Depending on the reaction conditions, three types of synthetic zeolites were formed: Na-X (20 g fly ash, 0.5 dm(3) of 3 mol · dm(-3) NaOH, 75 °C), Na-P1 (20 g fly ash, 0.5 dm(3) of 3 mol · dm(-3) NaOH, 95 °C), and sodalite (20 g fly ash, 0.8 dm(3) of 5 mol · dm(-3) NaOH + 0.4 dm(3) of 3 mol · dm(-3) NaCl, 95 °C). As synthesized materials were characterized to obtain mineral composition (X-ray diffractometry, Scanning electron microscopy-energy dispersive spectrometry), adsorption properties (Brunauer-Emmett-Teller surface area, N2 isotherm adsorption/desorption), and ion exchange capacity. The most effective reaction for zeolite preparation was when sodalite was formed and the quantitative content of zeolite from X-ray diffractometry was 90 wt%, compared with 70 wt% for the Na-X and 75 wt% for the Na-P1. Residues from each synthesis reaction were the following: mullite, quartz, and the remains of amorphous aluminosilicate glass. The best zeolitic material as characterized by highest specific surface area was Na-X at almost 166 m(2) · g(-1), while for the Na-P1 and sodalite it was 71 and 33 m(2) · g(-1), respectively. The ion exchange capacity decreased in the following order: Na-X at 1.8 meq · g(-1), Na-P1 at 0.72 meq · g(-1), and sodalite at 0.56 meq · g(-1). The resulting zeolites are competitive for commercially available materials and are used as ion exchangers in industrial wastewater and soil decontamination.

This paper presents a sub-pilot scale process of synthesis of Na-P1 zeolite from the coal fly ash. After establishing the appropriate synthesis conditions (20 kg of fly ash, 12 kg of NaOH, 90 dm3 of water, the reaction temperature: 80 °C and reaction time: 36 h), the high-purity (81 wt%) Na-P1 zeolite product was obtained. Its chemical, mineralogical, and textural properties were determined (by means of XRD, XRF, SEM–EDS and ASAP 2020). The synthesized material has a specific BET surface area (88 m2/g) c.a. six times higher than the fly ash from which it has been derived (15 m2/g). The pore-size distribution indicates a mesoporous character of the obtained zeolite, with the following pores size contents: micropores (2.76 %), mesopores (61.81 %), and macropores (35.43 %). The presented technological/production line is fully automated and allows to regulate the conditions of the synthesis process, therefore different types of zeolite materials (including: Na-X, Linde-A, and Na-P1) can be obtained using the same equipment.

This chapter is devoted to the theories of crystal growth and overall crystallization. The main postulate of different models of growth kinetics of imperfect smooth faces is that the presence of a screw dislocation, because of its geometry, ensures a continuous source of steps for the integration of growth entities on a growing surface and that there is no need for 2D nucleation involving an activation barrier. The discussion of the roughness of a step is for a crystal-vapor system, but the arguments are valid for the case of crystal-melt and crystal-solution interfaces. Impurities can also affect the kinetic and thermodynamic terms involved in different growth models. Kinetic roughening is connected with the size of the critical 2D nucleus, which approaches the size of an atom or molecule on the surface. The theoretical expressions for mononuclear or polynuclear mechanism and for instantaneous or progressive nucleation are different from each other.

Due to the key role of the biological decomposition process of organic compounds in wastewater treatment, a very important thing is appropriate aeration of activated sludge, because microorganisms have to be supplied with an appropriate amount of oxygen. Aeration is one of the most energy-consuming processes in the conventional activated sludge systems of wastewater treatment technology (may consume from 50% to 90% of electricity used by a plant), which makes it the most cost-generating process incurred by treatment plants. The paper presents the construction of aeration systems, their classification as well as parameters and factors that significantly affect the aeration process e.g., oxygen transfer efficiency, diffuser fouling, methods of dealing with diffuser fouling, diffuser selection. Additionally, there are briefly presented “smart control” systems in wastewater treatment and effect of application control strategy based on Supervisory Control and Data Acquisition system connected with the decrease in the energy consumption for aeration of bioreactors with activated sludge. It is noted that before the process is optimized, the system should be equipped with suitable metering devices. Only when relevant data is available, the improvements can be carried out. However, it’s important, that the operator should regularly maintain good condition and high efficiency of diffusers.

A review on works that investigate the mechanical behaviour of variable stiffness composite laminated panels is carried out in this paper. The review mostly focuses on buckling, failure and vibrations in laminates reinforced by curvilinear fibres, although other issues related to variable stiffness laminates are also addressed. The peculiarities in the formulation of curvilinear fibre reinforced plates are briefly described. As an illustration, the natural frequencies of vibration of variable stiffness composite laminated plates with curvilinear fibres are computed by an h-version type finite element code and are compared with the ones calculated using another model, based on a Third-order Shear Deformation Theory. Areas of research to explore on variable stiffness composite laminates are suggested.

Buildings are constructed and operated to satisfy human needs and improve quality of life. Good indoor air quality (IAQ) and thermal comfort are prerequisites for human health and well-being. For their provision, buildings often rely on heating, ventilation, and air conditioning (HVAC) systems, which may lead to higher energy consumption. This directly impacts energy efficiency goals and the linked climate change considerations. The balance between energy use, optimum IAQ and thermal comfort calls for scientifically solid and well-established limit values for exposures experienced by building occupants in indoor spaces, including homes, schools, and offices. The present paper aims to appraise limit values for selected indoor pollutants reported in the scientific literature, and to present how they are handled in international and national guidelines and standards. The pollutants include carbon dioxide (CO2), formaldehyde (CH2O), particulate matter (PM), nitrogen dioxide (NO2), carbon monoxide (CO), and radon (Rn). Furthermore, acknowledging the particularly strong impact on energy use from HVAC, ventilation, indoor temperature (T), and relative humidity (RH) are also included, as they relate to both thermal comfort and the possibilities to avoid moisture related problems, such as mould growth and proliferation of house dust mites. Examples of national regulations for these parameters are presented, both in relation to human requirements in buildings and considering aspects related to energy saving. The work is based on the Indoor Environmental Quality (IEQ) guidelines database, which spans across countries and institutions, and aids in taking steps in the direction towards a more uniform guidance for values of indoor parameters. The database is coordinated by the Scientific and Technical Committee (STC) 34, as part of ISIAQ, the International Society of Indoor Air Quality and Climate.

Surfaces are often characterized by their points of zero charge (PZC) and isoelectric points (IEP). Different authors use these terms for different quantities, which may be equal to the actual PZC under certain conditions. Several popular methods lead to results which are inappropriately termed PZC. This present review is limited to zero-points obtained in the presence of inert electrolytes (halides, nitrates, and perchlorates of the 1st group metals). IEP are reported for all kinds of materials. PZC of metal oxides obtained as common intersection points of potentiometric curves for 3 or more ionic strengths (or by means of equivalent methods) are also reported, while the apparent PZC obtained by mass titration, pH-drift method, etc. are deliberately neglected. The results published in the recent publications and older results overlooked in the previous compilations by the same author are reported. The PZC/IEP are accompanied by information on the temperature and on the nature and concentration of supporting electrolyte (if available). The references to previous reviews by the same author allow to compare the newest results with the PZC/IEP of similar materials from the older literature.

Abstract There is only a scant possibility of today's environmental problems being solved solely by technical means, with no account being taken of the social or economic aspects. Thus, three generally recognized dimensions of sustainable development have been devised: ecological, social and economic. However, the basis for them is moral reflection regarding humankind's responsibility for nature. Is this all? Perhaps we should also include technical, legal and political dimensions. All of them are important and all of them are characterized in this paper. Since they are connected with one another, examples of the degree to which they can overlap are also discussed. Copyright © 2007 John Wiley & Sons, Ltd and ERP Environment.

A critical review of the points of zero charge (PZC) obtained by potentiometric titration and of isoelectric points (IEP) obtained by electrokinetic measurements. The results from the recent literature are presented with experimental details (temperature, method, type of apparatus, etc.), and they are compared with the zero points of similar materials reported in older publications. Most studies of PZC and IEP reported in the recent papers were carried out for metal oxides and hydroxides, especially alumina, iron oxides, and titania, and the results are consistent with the PZC and IEP of similar materials reported in older literature, and summarized in previous reviews by the same author. Relatively few studies were carried out with less common materials, and IEP of (nominally) VO2 and BN have been reported for the 1st time.

Manufacturing is experiencing relevant changes under the challenges imposed by the sustainable economic development model. Under this model, the significant progress in advanced technologies is providing new opportunities to enhance competitiveness. Meanwhile, the maintenance function is transforming its role in order to better support value creation, both contributing to the economic dimension as well as extending its care for the environmental and social aspects. Maintenance 4.0 can break the trade-offs of the older strategies by enabling companies to maximize the useful life of their production equipment while avoiding unplanned downtime, minimizing planned downtime, increasing process and people safety, minimizing energy and resources consumption and saving costs. The paper presents the possibility of incorporation new technologies into the planning, implementation, monitoring and analysis of maintenance processes that support sustainable production in modern manufacturing companies.