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This paper aims to present the details of isotactic polypropylene (it-PP) films with a cellular structure (air-cavities) dedicated to pressure sensors. The polymer composites (thin films enriched with 5 and 10 wt% of mineral fillers as Sillikolloid P 87 and glass beads) should exhibit suitable structural elasticity within specific stress ranges. After the deformation force is removed, the sensor material must completely restore its original shape and size.

Estimating the stiffness tensor element (C₃₃) for polymer films (nonpolar space-charge electrets) by broadband resonance ultrasound spectroscopy is a relatively simple method of determining the safe stress range generated in thin pressure sensors. Therefore, ultrasonic and piezoelectric studies were carried out on four composite it-PP films. First, the longitudinal velocity (v_L) of ultrasonic waves passing through the it-PP film in the z-direction (thickness) was evaluated from the ω-position of mechanical resonance of the so-called insertion loss function. In turn, the d₃₃ coefficient was calculated from accumulated piezoelectric charge density response to mechanical stress.

Research is at an early stage; however, it can be seen that the mechanical orientation of the it-PP film improves its piezoelectric properties. Moreover, the three-year electric charge stability of the it-PP film seems promising.

Ultrasonic spectroscopy can be successfully handled as a validation method in the small-lot production of polymer films with the air-cavities structure intended for pressure sensors. The structural repeatability of polymer films is strongly related to a homogeneous distribution of the electric charge on the electret surface.

Cotton-comfortable multi-ply face mask fabrics have been developed at The University of Tennessee's Textiles and Nonwovens Development Center (TANDEC) which have a repellent finished outer spunbond (SB) polypropylene (PP) layer, a middle layer of electrostatically charged (EC) melt blown (MB) PP, and a face side of a cotton-rich nonwoven. The EC MB PP layer effectively filters out aerosols and particulate containing bacteria and viruses, thereby protecting both the wearer and other personnel in the environment. In addition, a cotton-rich nonwoven layer on the body side provides the aesthetics and comfort of cotton, and also better retains antibacterial finish for neutralizing any microbes that penetrate the EC filter media. Filtration efficiency (FE) against 0.1 μm NaCl particles and the pressure drop were determined at TANDEC. FE to water aerosol containing Staphyloccus aureus bacteria per the In Vitro Bacterial Filtration Efficiency (BFE) test and to virus (φX174) per the In Vitro Viral Filtration Efficiency (VFE) were determined at Nelson Laboratories. The percent reduction of bacteria after the BFE test was also ascertained by Nelson Laboratories by a method adapted from AATCC 100.

The purpose of this paper is to elucidate best approaches for facility radon management in a resource-limited environment such as a public university. Radon exposures are believed to be a risk factor for lung cancer. However, the degree to which typical indoor radon levels within settings such as the university campus contribute to lung cancer risk is controversial. The authors sought to develop a risk-balancing approach to safe and cost-efficient facility radon management.

The authors collected pilot monitoring data to determine radon activity levels at a large public university within a projected high-radon region of the southeastern USA, then reviewed scientific literature, trade literature and regulatory guidance to determine radon risk knowledge and best practices for mitigation. From this body of data and information, the authors determined the safest and most resource-effective means for campus radon management.

The developed program for comprehensive radon management included guidance on building selection for most effective use of monitoring, tiered response and mitigation strategies based on radon activity levels and faculty, staff and student education.

The radon management strategies might not be generalizable to facilities with usage patterns that differ from a public university, and should be extrapolated with caution.

This paper shows how building managers can address indoor radon in a manner that maximizes both safety and cost-efficiency.

This paper fulfills a need for evidence-based and prudent approaches to radon management for campuses with mixed residential, educational and occupational contexts and limited resources.

Cleanrooms are highly controlled enclosed rooms where air quality is monitored and ensured to have less contamination according to standard cleanliness level. Air filters are used to optimize indoor air quality and remove air pollutants. Filter media and filtering system are decided as per requirement. Depth filter media are mostly used in cleanroom filtrations. This paper aims to present a comprehensive review of the evolution of cleanroom filter media. It evaluates the advantages and disadvantages of air filter media. It is also studied which air filters have additional properties such as anti-microbial properties, anti-odour properties and chemical absorbent. Development and innovation of air filters and filtration techniques are necessary to improve the performance via the synergistic effect and it can be a possible avenue of future research.

This paper aims to drive the future of air filter research and development in achieving high-performance filtration with high filtration efficiency, low operational cost and high durability. Air pollutants are classified into three types: suspended particles, volatile organic pollutants and microorganisms. Technologies involved in purification are filtration, water washing purification, electrostatic precipitation and anion technology. They purify the air by running it through a filter medium that traps dust, hair, pet fur and debris. As air passes through the filter media, they function as a sieve, capturing particles. The fibres in the filter medium provide a winding path for airflow. There are different types of air filters such as the high-efficiency particulate air filter, fibreglass air filter and ultra-low particulate air filter.

Emerging filtration technologies and filters such as nanofibres, filters with polytetrafluoroethylene membrane are likely to become prevalent over the coming years globally. The introduction of indoor air filtration with thermal comfort can be a possible avenue of future research along with expanding indoor environment monitoring and improving air quality predictions. New air filters and filtration technologies having better performance with low cost and high durability must be developed which can restrict multiple types of pollutants at the same time.

The systematic literature review approach used in this paper highlights the emerging trends and issues in cleanroom filtration in a structured and thematic manner, enabling future work to progress as it will continue to develop and evolve.

This paper aims to present a prototype of the diagnostic system for the examination of the distribution of the force applied by foot to substrate during usual human moving. Presented system is competitive to other currently available devices, thanks to sensors reliability, user-friendly operation manner and design based on cheap parts. The results of examinations are transmitted by radiomodem. Its recording and visualization are possible on either personal or mobile computers.

During selection of the sensors substrate, many polymeric electrets were examined. Polyvinylidene fluoride films were selected, because they have good charge uniformity across the surface, wide range of acceptable temperatures, linear relation between mechanical stress and output signal and high resistance for squeezing. The system measures the charge generated in film.

The pressures are recorded in relation to maximum value; therefore, measuring system does not require calibration. The simultaneous recording of data from all eight sensors allows tracking the signal without distortion.

An array of sensors is installed in the shoe insole. The measuring device is fixed to the outer surface of the shoe. Its weight is 75 g. The range of transmission is suitable for examination in the natural environment, outside traditional consulting room. Software is dedicated for analysis of the pressure distribution in every moment of the foot movement. The system is suitable for examination of flat feet, diabetic foot and recovery progress after injures.

This paper aims to provide details of recent energy harvesting developments.

Following an introduction, this paper first considers mechanical and biomechanical energy harvesting developments. It then discusses hybrid harvesting technologies and self-powered sensors and concludes with a brief discussion.

Energy harvesting is the topic of a major research effort and growing commercial activities. Several advanced technologies are being used to develop sophisticated devices to harvest individual or combined energy sources. These developments are expected to play a central role in many emerging sensor markets.

This paper provides technical details of a selection of recently reported energy harvesting developments.

The purpose of this paper is to provide an overview of the human factors/ergonomics (HFE) studies for respirator.

This review paper describes and discusses the various factors and methodologies of HFE, for the purpose of better considering human factors, used in respirator studies and further human-centered product development.

Many attempts have been made to study human factors for respirators mainly including fit, human performance, comfort, and mood. Physical, psychological, and physiological indices of people are extremely valuable to HFE studies for respirator. Objective and subjective measures were methodologies widely used. Quantitative and qualitative approaches were adopted to illustrate the human performance and well-being influenced by respirators. A summary table presented with major methods used for indices of respirators in the field of HFE. According to the current researches, this review indicated three particular challenges facing HFE studies of respirators now.

With the ever increasing role of protection from air pollution in society, respirator has become an increasingly important part of our daily lives. HFE intervene in optimizing the relationships between respirators and the human using them. Plenty of efforts have been dedicated for the development of protection capability, but HFE studies for respirators are lacking. In recent years, there has been a tremendous interest in introducing HFE research methods that can evaluate respirators from the perspective of human and translate them into constraints for designing human-centered respirators.

This is a first paper in the field of HFE studies for respirator, which will remain helpful to the scientific community to start further human-centered research work and product development.

International outbreak of the SARS-CoV-2 infection has fostered the Italian government to impose the FFP2 protective facial masks in closed environments, including bar, restaurants and, more in general, in the food sector. Protective facial masks are rocketing, both in mass and in costs, in the food sector imposing efforts in fostering reuse strategies and in the achievement of sustainable development goals. The scope of the present paper is to depict possible strategies in manufacturing and reuse strategies that can reduce the carbon footprint (CF) of such devices.

To implement circular economy strategies in the protective facial masks supply chain, it was considered significant to move towards a study of the environmental impact of such devices, and therefore a CF study has been performed on an FFP2 facial mask used in the food sector. Different materials besides the mostly used polypropylene (PP) (polyethylene (PE), polycarbonate (PC), poly (lactic acid) (PLA), cotton, polyurethane (PUR), polystyrene (PS) and nylon 6,6) and different sanitisation alternatives as reuse strategies (both laboratory and homemade static oven, ultraviolet germicidal irradiation) readily implemented have been modelled to calculate the CF of a single use of an FFP2 mask.

The production of textiles in PP, followed by disposal was the main contributor to CF of the single-use FFP2 mask, followed by packaging and transportations. PP and PE were the least impacting, PC, cotton and Nylon 6-6 of the same weight results the worst. PLA has an impact greater than PP and PE obtained from crude oil, followed by PUR and PS. Static laboratory oven obtained an 80.4% reduction of CF with respect to single use PP-made FFP2 mask, whereas homemade oven obtained a similar 82.2% reduction; UV cabinet is the best option, showing an 89.9% reduction.

The key strategies to reduce the environmental impacts of the masks (research for new materials and reuse with sanitisation) should ensure both the retention of filtering capacities and the sanitary sterility of the reused ones. Future developments should include evaluations of textile recycling impacts, using new materials and the evaluation of the life cycle costs of the reused masks.

This paper intends to provide to stakeholders (producers, consumers and policy makers) the tools to choose the best option for producing and reuse environmentally friendly protective facial masks to be used in the food sector, by using both different materials and easily implemented reuse strategies.

The reduction of the CF of protective facial masks in the food sector surely will have relevant positive effects on climate change contributing to reach the goals of reducing CO₂ emissions. The food sector may promote sustainable practices and attract a niche piece of clients particularly sensible to such themes.

The paper has two major novelties. The first one is the assessment of the CF of a single use of an FFP2 mask made with different materials of the non-woven filtering layers; as the major contribution to the CF of FFP2 masks is related to the non-woven textiles manufacturing, the authors test some other different materials, including PLA. The second is the assessment of the CF of one single use of a sanitised FFP2 mask, using different sanitation technologies as those allowed in bars or restaurants.

The thermal diffusivity of thick film NTC layers based on a metal oxide powder mixture was measured at room temperature by the photoacoustic (PA) technique. The powder mixture was composed of MnO (60 percent), CoO (32 percent) and Fe₂O₃ (8 percent), which were ball milled to nanometer particle size. NTC layers of different thicknesses were made by sequentional screen‐printing followed by drying and co‐firing at 850, 900 and 1,000°C in a hybrid conveyor furnace. The experimental PA phase and amplitude diagrams were numerically analyzed and the thermal diffusivity and electron transport parameters were calculated. An increase of thermal diffusivity with sintering temperature was observed. The fractal structure model was in agreement with the experimental data for modulation frequencies in which the sample behaved as thermally thick.