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This study investigates the fabrication and characterization of innovative electrical devices (EDs) subjected to an alternating electric field in the presence of static electric and magnetic fields. The EDs contain suspensions of silicone oil (SO) and micrometric aggregates of polypyrrole nanotubes decorated with various mass fractions of magnetite nanoparticles (PPyM). Our experimental findings and theoretical analyses demonstrate that the conductance and susceptance of these EDs can be coarsely adjusted by altering the mass ratios of magnetite to polypyrrole. Fine control of these electrical properties is achieved through the application of electric and magnetic fields superimposed on the alternating electric field. The findings reveal the dual responsiveness of the EDs at small values of electric and magnetic field intensities. A theoretical model is proposed that provides a qualitative description of the physical mechanisms governing the behavior of the EDs under these field conditions. Thus, the results contribute to advancing the understanding of electromagnetorheological phenomena at the microscale in this type of ED, highlighting the potential of PPyM composites dispersed within an SO matrix, in the development of sophisticated micromachines with dynamically controllable features under varying external conditions. [ABSTRACT FROM AUTHOR]

This study aims to develop low-cost, eco-friendly, and circular economy-compliant composite materials by creating three types of magnetorheological suspensions (MRSs) utilizing lard, carbonyl iron (CI) microparticles, and varying quantities of gelatin particles (GP). These MRSs serve as dielectric materials in cylindrical cells used to fabricate electric capacitors. The equivalent electrical capacitance (C) of these capacitors is measured under different magnetic flux densities ( B ≤ 160 mT) superimposed on a medium-frequency electric field (f = 1 kHz) over a period of 120 s. The results indicate that at high values of B, increasing the GP content to 20 vol.% decreases the capacitance C up to about one order of magnitude compared to MRS without GP. From the measured data, the average values of capacitance C m are derived, enabling the calculation of relative dielectric permittivities ( ϵ r ′ ) and the dynamic viscosities (η) of the MRSs. It is demonstrated that ϵ r ′ and η can be adjusted by modifying the MRS composition and fine-tuned through the magnetic flux density B. A theoretical model based on the theory of dipolar approximations is used to show that ϵ r ′ , η , and the magnetodielectric effect can be coarsely adjusted through the composition of MRSs and finely adjusted through the values B of the magnetic flux density. The ability to fine-tune these properties highlights the versatility of these materials, making them suitable for applications in various industries, including electronics, automotive, and aerospace. [ABSTRACT FROM AUTHOR]

This paper presents the fabrication and characterization of plane capacitors utilizing magnetodielectric materials composed of magnetizable microfibers dispersed within a silicone oil matrix. The microfibers, with a mean diameter of about 0.94 μ m, comprise hematite (α -Fe2O3), maghemite (γ -Fe2O3), and magnetite (Fe3O4). This study investigates the electrical behavior of these capacitors under the influence of an external magnetic field superimposed on a medium-frequency alternating electric field, across four distinct volume concentrations of microfibers. Electrical capacitance and resistance measurements were conducted every second over a 60-s interval, revealing significant dependencies on both the quantity of magnetizable phase and the applied magnetic flux density. Furthermore, the temporal stability of the capacitors' characteristics is demonstrated. The obtained data are analyzed to determine the electrical conductance and susceptance of the capacitors, elucidating their sensitivity to variations in microfiber concentration and magnetic field strength. To provide theoretical insight into the observed phenomena, a model based on dipolar approximations is proposed. This model effectively explains the underlying physical mechanisms governing the electrical properties of the capacitors. These findings offer valuable insights into the design and optimization of magnetodielectric-based capacitors for diverse applications in microelectronics and sensor technologies. [ABSTRACT FROM AUTHOR]

In today’s economy increased attention is given towards re-using of available resources and using of resources which are re-generable, to evaluate and reduce the impact on the environment. For the polymer industry, the development of alternative and renewable raw materials represents an essential task. The study evaluates the different choices of unsaturated polyester resins (UPR) for production of centrifugally-cast glass reinforced pipe (cc-GRP) systems. The environmental impacts of three types of resin were evaluated and compared. The resins are: UPR standard, UPR containing recycled PET material (rPET-UPR) and UPR containing bio-sourced material (BIO-UPR). The analysis focuses on comparing the variations in environmental indicators caused by resin selection for three increasingly complex product layers (Base plate of cc-GRP shaft, cc-GRP Shaft and 1km cc-GRP Pipe-system). The study equally provides an insight onto R&D and LCA collaboration across the supply-chain. One of the main challenges in LCA today is using specific data from the suppliers instead of generic data. The paper indicates how LCA tools and established R&D processes can be employed to transfer LCA calculations across the supply-chain. BIO-UPR and rPET-UPR are alternatives which are realistic in terms of costs and which ensure the required quality for the manufactured products. rPET-UPR can be used for production of complete pipe systems, with positive environmental indicators. Mechanical proprieties of BIO-UPR restrict its usability and use of this resin presents similarities with the debate regarding use of bio-diesel.

Water is an essential factor of the population existence and health and a primordial condition for the evolution of the society. In the context of climate change that determines the reduction of resources, the sustainable use of water, are key factors of sustainable development. The spatial and temporal distribution of water is determined not only by economic activities and the degree of urbanization, but also by natural variations in climate as a result of climate change. In recent decades, there has been a growing awareness of the value of stormwater as a resource that must be considered in urban development. In the context of the deterioration of the ecological conditions of water sources, due to pollution on the one hand, population growth and the influx of people into urban areas, on the other hand, the challenge for cities is to balance the limited supply and the growing demand for water. In recent years, migration is an additional challenge for the urban development strategy. At the same time, water as a resource and related infrastructure are among the most vulnerable sectors during armed conflicts. [ABSTRACT FROM AUTHOR]

The paper presents a methodology to assess the solutions for the management of contaminated sites. For defining these solutions there were developed two main activities. First one consists in a detailed site investigation to define its geological, hydrogeological characteristics and surely the contamination level. The second activity is dedicated to the assessment of risk generated by the soil, subsoil, air, and groundwater contamination, by using a professional software. The methodology was applied to a real case study. The results showed that for non-carcinogenic compounds the risk is above the thresholds establish by legislation. The conclusion is that measures to mitigate this risk must be taken, based on a feasibility study that will be realised in the next stage of the research.

The past human activities, mainly that related to industrial development caused in many cases a strong contamination of soil, subsoil environment and of groundwater. This type of pollution is a concern because it poses risks to human health and to the ecosystem. More than this, such areas may not be used for new development, requiring solutions for remediation. The management of these sites consists of three main activities: characterization, remediation and, finally, redevelopment. The paper presents a case study dedicated to the first step of contaminated sites management, respectively characterization. This phase is very important, a good characterization could ensure a performant solution for the second step – remediation. Two new techniques for site characterization are presented, as technical principles, but also as performances obtained for the mentioned case study.

Over the past few decades, tactile sensors have become an emerging field of research with direct applications in the area of biomedical engineering. New types of tactile sensors, called magneto-tactile sensors, have recently been developed. The aim of our work was to create a low-cost composite whose electrical conductivity depends on mechanical compressions that can be finely tuned using a magnetic field for magneto-tactile sensor fabrication. For this purpose, 100% cotton fabric was impregnated with a magnetic liquid (EFH-1 type) based on light mineral oil and magnetite particles. The new composite was used to manufacture an electrical device. With the experimental installation described in this study, we measured the electrical resistance of an electrical device placed in a magnetic field in the absence or presence of uniform compressions. The effect of uniform compressions and the magnetic field was the induction of mechanical–magneto–elastic deformations and, as a result, variations in electrical conductivity. In a magnetic field with a flux density of 390 mT, in the absence of mechanical compression forces, a magnetic pressure of 5.36 kPa was generated, and the electrical conductivity increased by 400% compared to that of the composite in the absence of a magnetic field. Upon increasing the compression force to 9 N, in the absence of a magnetic field, the electrical conductivity increased by about 300% compared to that of the device in the absence of compression forces and a magnetic field. In the presence of a magnetic flux density of 390 mT, and when the compression force increased from 3 N to 9 N, the electrical conductivity increased by 2800%. These results suggest the new composite is a promising material for magneto-tactile sensors. [ABSTRACT FROM AUTHOR]

The paper presents the experimental installation for the production, in argon plasma, of cavitational iron microparticles (pore microspheres, microtubes and octopus-shaped microparticles). Experimental results are presented and discussed and it is shown that absorbant particles with a minimum iron content are obtained by the plasma procedures

The circular economy development has increased awareness on how construction products are treated at the end-of-life stage (EoL). With a growing recognition of the finite nature of primary resources, manufacturing processes are being shifted from the traditional take-make-dispose approach to a greater holistic practice, where valuable and/or scarce substances are recovered at the end of a product’s life. Life Cycle Assessment (LCA) is gaining wider attractiveness, as assessment of environmental impacts constitutes an effective quantitative decision tool to identifying sustainable solutions. At the same time, existing guidelines, technical specifications and methods for LCA assessment at EoL are rather heterogeneous regarding modelling and calculation of related secondary material and energy streams. For construction products, category rules for Environmental Product Declarations (EPD) according to EN 15804 (issued through the European Committee for Standardization) and the Product Environmental Footprint (PEF) (developed by the European Commission) currently represent the most advanced methodological references. The study presents the methodological approach per EN 15804, describing the benefits and loads beyond the typical disposal stage. Thus, the environmental impacts of a construction element can be credited in accord to its material and energetic recycling potential. An applied model is realized for water pipes made of composite material. The calculation is exemplified and comparative results of allocation scenarios per EN 15804 and PEF are discussed, demonstrating correlations between the normative requirements and their application. The results support further identification, assessment and ranking of recycling alternatives (i.e. mechanical, thermal, chemical).