Search Results (1,054)

The increasing focus on environmental sustainability has prompted the healthcare sector, including dentistry, to reconsider waste management practices. Dental offices generate various waste streams from outdated technologies, including single-use plastics, hazardous materials, and digital waste. This scoping review explores how integrating circular economy principles with lean management practices can enhance sustainability and operational efficiency in dental clinics. Using the PRISMA methodology, the review identifies 30 articles that passed the Cochrane Risk of Bias Tool and the Critical Appraisal Skills Program (CASP) checklist from 2000. Circular economy principles focus on reducing waste and maximizing resource reuse, while lean management seeks to improve efficiency and minimize process waste. Together, these approaches can significantly reduce resource consumption and enhance recycling efforts in dental practices. Despite barriers such as high technology costs, regulatory constraints, and limited recycling infrastructure, case studies highlight successful implementation in healthcare settings, demonstrating improved environmental and operational outcomes. Collaboration between dental professionals, policymakers, and industry leaders is essential for promoting the adoption of these sustainable practices. Full article

Over the past 50 years, global plastic production has surged exponentially. Around 40% of this plastic is used for packaging, most of which is single-use, while 20% is used in construction. Despite the vast quantities produced, only about 6% of discarded plastics are properly recycled, 10% are incinerated, and the majority are disposed of without proper management. With low recycling rates and some plastics being non-recyclable or with limited recycling cycles, it is important to explore new ways of reusing this waste as secondary raw materials. This study explores the potential of incorporating non-recyclable plastic waste into bituminous mixtures. The objective is to develop a sustainable solution for surface courses with similar or better performance than traditional bituminous mixtures by incorporating plastic waste using the dry method. A bituminous mixture containing 10% non-recyclable plastic was formulated and tested for water sensitivity, wheel tracking, and stiffness modulus. Additionally, environmental and economic comparisons were performed with a standard surface mixture. Results showed increased water resistance, high resistance to permanent deformation, reduced stiffness, lower susceptibility to frequency and temperature variations, and greater flexibility. These findings suggest that adding plastic not only enhances mechanical properties but also reduces costs, offering a sustainable alternative for non-recyclable plastics in road construction. Full article

In this study, we used the depth-sensing indentation technique to determine the cracking resistance of different PVD hard coatings deposited on tool steel substrates. By comparison, with the load–displacement curves, measured at the sites of carbide inclusion and a tempered martensite matrix in the D2 tool steel substrate surface, we observed different fracture mechanisms on TiAlN hard coating prepared by sputtering. Additional information about the deformation and fracture phenomena was obtained from the SEM images of FIB cross-sections of both types of indents. We found that the main deformation mechanism in the coating is the shear sliding along the columnar boundaries, which causes the formation of steps on the substrate surface under individual columns. Using nanoindentation test, we also analyzed the cracking resistance of a set of nl-(Cr,Al)N nanolayer coatings with different Cr/Al atomic ratios, which were sputter deposited in a single batch. From the indentation curves, we determined the loads (F_c) at which the first pop-in appears and compared them with the plasticity index H³/E². A good correlation of both parameters was found. We also compared the indentation curves of the TiAlN coating, which were prepared by cathodic arc evaporation using 1-fold, 2-fold and 3-fold rotation of the substrates. Additionally, on the same set of samples, the fracture toughness measurements were performed by micro-cantilever deflection test. The impact of growth defects on the cracking resistance of the hard coatings was also confirmed. Full article

Earlier, I created a mathematical model of the gear unit, in which the value of the tooth friction was determined during precalculation and then entered into the model as a constant parameter. In this paper, I investigate how much viscosity oil is required at different operating points for a single-stage gear unit with plastic gears to function properly and how this affects the tooth friction and, hence, the loss of energy in the gear unit. Once the investigations are complete, the tooth friction is determined using an automated MATLAB function, which allows the tooth friction to be re-determined at each operating point. This allows for a more accurate strength dimensioning of the plastic gears in the gear unit and a more accurate model describing the gear unit’s behaviour. Full article

The social impacts of prevailing circular economy (CE) strategies remain under-researched despite the considerable attention that CE has received from scholars and in industry. Existing CE indicators primarily focus on business models from a decision-making standpoint, overlooking consumer engagement and alternative solutions. Boasting one of the highest recycling rates globally, Taiwan faces challenges in optimizing collected resources. This study delves into recycling plastic waste by integrating consumer behavior within CE strategies, leveraging open-source resources and additive manufacturing technologies to align with the United Nations Agenda 2030, particularly Sustainable Development Goals (SDGs) 4 (Quality Education), 12 (Responsible Consumption and Production), and 13 (Climate Action). These resources facilitate the transformation of plastic waste into reusable materials. Employing an exploratory and participatory action research approach, this research uses the Precious Plastic Universe (PPU) database to identify potential resources from post-consumer polymer waste. Subsequently, it explores tools for converting collected waste into usable polymers. Lastly, the study investigates integrating collected polymer waste into student design projects to enhance creativity and problem-solving skills for sustainable development, employing additive manufacturing tools at the National Taiwan Normal University Department of Design. Thematic analysis of the data revealed several recurring patterns, including the role of consumer behavior in plastic waste generation, the development of creativity and problem-solving skills among students, and the challenges of working with recycled materials. These themes were observed in quantitative data (collected single-use polymers) and qualitative insights from student observations and interviews. Through thematic analysis, the study highlights key factors contributing to successful CE integration, providing a model for future educational and industrial applications of sustainable design. Full article

Neuronal spike patterns are the fundamental units of neural communication in the brain, which is still not fully understood. Entropy measures offer a quantitative framework to assess the variability and information content of these spike patterns. By quantifying the uncertainty and informational content of neuronal patterns, entropy measures provide insights into neural coding strategies, synaptic plasticity, network dynamics, and cognitive processes. Here, we review basic entropy metrics and then we provide examples of recent advancements in using entropy as a tool to improve our understanding of neuronal processing. It focuses especially on studies on critical dynamics in neural networks and the relation of entropy to predictive coding and cortical communication. We highlight the necessity of expanding entropy measures from single neurons to encompass multi-neuronal activity patterns, as cortical circuits communicate through coordinated spatiotemporal activity patterns, called neuronal packets. We discuss how the sequential and partially stereotypical nature of neuronal packets influences the entropy of cortical communication. Stereotypy reduces entropy by enhancing reliability and predictability in neural signaling, while variability within packets increases entropy, allowing for greater information capacity. This balance between stereotypy and variability supports both robustness and flexibility in cortical information processing. We also review challenges in applying entropy to analyze such spatiotemporal neuronal spike patterns, notably, the “curse of dimensionality” in estimating entropy for high-dimensional neuronal data. Finally, we discuss strategies to overcome these challenges, including dimensionality reduction techniques, advanced entropy estimators, sparse coding schemes, and the integration of machine learning approaches. Thus, this work summarizes the most recent developments on how entropy measures contribute to our understanding of principles underlying neural coding. Full article

Most single-screw extruders used in the plastics processing industry are plasticizing extruders, designed to melt solid pellets or powders within the screw channel during processing. In many cases, the efficiency of the melting process acts as the primary throughput-limiting factor. If the material melts too late in the process, it may not be sufficiently mixed, resulting in substandard product quality. Accurate prediction of the melting process is therefore essential for efficient and cost-effective machine design. A practical method for engineers is the modeling of the melting process using mathematical–physical models that can be solved without complex numerical methods. These models enable rapid calculations while still providing sufficient predictive accuracy. This study revisits the modified Tadmor model by Potente, which describes the melting process and predicts the delay-zone length, extending from the hopper front edge to the point of melt pool formation. Based on extensive experimental investigations, this model is adapted by redefining the flow temperatures at the phase boundary and accounting for surface porosity at the beginning of the melting zone. Additionally, the effect of variable solid bed dynamics on model accuracy is examined. Significant model improvements were achieved by accounting for reduced heat flow into the solid bed due to the porous surface structure in the solid conveying zone, along with a new assumption for the flow temperature at the phase boundary between the solid bed and melt film. Full article

Efficiently simulating solid mechanics is vital across various engineering applications. As constitutive models grow more complex and simulations scale up in size, harnessing the capabilities of modern computer architectures has become essential for achieving timely results. This paper presents advancements in running parallel simulations of solid mechanics on multi-core CPUs and GPUs using a single-code implementation. This portability is made possible by the C++ matrix and array (MATAR) library, which interfaces with the C++ Kokkos library, enabling the selection of fine-grained parallelism backends (e.g., CUDA, HIP, OpenMP, pthreads, etc.) at compile time. MATAR simplifies the transition from Fortran to C++ and Kokkos, making it easier to modernize legacy solid mechanics codes. We applied this approach to modernize a suite of constitutive models and to demonstrate substantial performance improvements across different computer architectures. This paper includes comparative performance studies using multi-core CPUs along with AMD and NVIDIA GPUs. Results are presented using a hypoelastic–plastic model, a crystal plasticity model, and the viscoplastic self-consistent generalized material model (VPSC-GMM). The results underscore the potential of using the MATAR library and modern computer architectures to accelerate solid mechanics simulations. Full article

Aqueous phase reforming (APR) is a promising method for producing hydrogen from biomass-derived feedstocks. In this study, carbon-supported Pt catalysts containing particles of different sizes (below 3 nm) were deposited on different commercially available carbons (i.e., Vulcan XC72 and Ketjenblack EC-600JD) using the metal vapor synthesis approach, and their catalytic efficiency and stability were evaluated in the aqueous phase reforming of ethylene glycol, the simplest polyol containing both C–C and C–O bonds. High-surface-area carbon supports were found to stabilize Pt nanoparticles with a mean diameter of 1.5 nm, preventing metal sintering. In contrast, Pt single atoms and clusters (below 0.5 nm) were not stable under the reaction conditions, contributing minimally to catalytic activity and promoting particle growth. The most effective catalyst Pt_A/C^K, containing a mean Pt NP size of 1.5 nm and highly dispersed on Ketjenblack carbon, demonstrated high hydrogen site time yield (8.92 min⁻¹ at 220 °C) and high stability under both high-temperature treatment conditions and over several recycling runs. The catalyst was also successfully applied to the APR of polyethylene terephthalate (PET), showing potential for hydrogen production from plastic waste. Full article

Ultrathin metal foils are essential for applications requiring miniaturization across modern industry. Nevertheless, it is challenging for conventional rolling mills and conventional rolling methods to reduce the thickness of single-layer foils to a scale approaching just a few micrometers. This difficulty arises from a range of inherent factors, including the elastic modulus, diameter of the rollers, resistance of rolled materials, and friction coefficient. To address these limitations, an accumulative pack rolling (APR) method has been developed in this work to fabricate ultrathin metal foils. Al foils down to ~2 µm have been successfully fabricated by using Al, Ta, and stainless steel (SS) as pack materials. The effects of the pack sheets on surface morphology, thickness reduction, and microstructural evolution were investigated. Key surface roughening behaviors, including ridging and particle-like surface roughening, were observed on the inner surface, which influences the roughening and thinning behavior of the target Al foils. This study also provides insights into surface roughening mechanisms, including rolling marks, ridging, and particle-like roughening, and demonstrates the critical role of pack sheet materials in controlling plastic instability, achieving uniform thickness reduction in ultrathin foils, and preventing severe deterioration of surface flatness during the APR process. Full article

The increasing production of plastics, driven by modern societal development, has resulted in a significant rise in plastic waste, which poses serious environmental concerns due to its lengthy degradation times. The growing issue of single-use plastics (SUPs), such as packaging for food items and disposable utensils, has led to their reduction and potential future prohibition in the European Union. Cellulose, a natural biopolymer sourced from nature, has been proposed as a viable alternative to SUPs because it degrades without toxicity. However, its limited barrier properties against water and grease have restricted its effectiveness as a substitute. This study focuses on developing an environmentally friendly alternative to SUPs by combining cellulose with acetylated starch and incorporating inorganic fillers like kaolin and talc. These fillers enhance the material’s barrier properties and reduce production costs. The results indicate that the addition of kaolin significantly lowers moisture absorption and water vapor permeability, while a mixture of kaolin and talc provides superior grease resistance. Additionally, incorporating D-sorbitol as a plasticizer improves the mechanical properties of the coated sheets, preventing cracking and enhancing strength. Overall, these coatings offer a promising alternative for packaging applications, such as for sugar, candies, or chocolate. Full article

Background: Humans cannot avoid plastic exposure due to its ubiquitous presence in the natural environment. The waste generated is poorly biodegradable and exists in the form of MPs, which can enter the human body primarily through the digestive tract, respiratory tract, or damaged skin and accumulate in various tissues by crossing biological membrane barriers. There is an increasing amount of research on the health effects of MPs. Most literature reports focus on the impact of plastics on the respiratory, digestive, reproductive, hormonal, nervous, and immune systems, as well as the metabolic effects of MPs accumulation leading to epidemics of obesity, diabetes, hypertension, and non-alcoholic fatty liver disease. MPs, as xenobiotics, undergo ADMET processes in the body, i.e., absorption, distribution, metabolism, and excretion, which are not fully understood. Of particular concern are the carcinogenic chemicals added to plastics during manufacturing or adsorbed from the environment, such as chlorinated paraffins, phthalates, phenols, and bisphenols, which can be released when absorbed by the body. The continuous increase in NMP exposure has accelerated during the SARS-CoV-2 pandemic when there was a need to use single-use plastic products in daily life. Therefore, there is an urgent need to diagnose problems related to the health effects of MP exposure and detection. Methods: We collected eligible publications mainly from PubMed published between 2017 and 2024. Results: In this review, we summarize the current knowledge on potential sources and routes of exposure, translocation pathways, identification methods, and carcinogenic potential confirmed by in vitro and in vivo studies. Additionally, we discuss the limitations of studies such as contamination during sample preparation and instrumental limitations constraints affecting imaging quality and MPs detection sensitivity. Conclusions: The assessment of MP content in samples should be performed according to the appropriate procedure and analytical technique to ensure Quality and Control (QA/QC). It was confirmed that MPs can be absorbed and accumulated in distant tissues, leading to an inflammatory response and initiation of signaling pathways responsible for malignant transformation. Full article

Sweet potato (Ipomoea batatas) is an important food crop that plays a pivotal role in preserving worldwide food security. Due to its polyploid genome, high heterogeneity, and phenotypic plasticity, sweet potato genetic characterization and breeding is challenging. Genome-wide association studies (GWASs) can provide important resources for breeders to improve breeding efficiency and effectiveness. GWASpoly was used to identify 28 single nucleotide polymorphisms (SNPs), comprising 21 unique genetic loci, associated with sweet potato storage root traits including dry matter (4 loci), subjective flesh color (5 loci), flesh hue angle (3 loci), and subjective skin color and skin hue angle (9 loci), in 384 accessions from the USDA sweet potato germplasm collection. The I. batatas ‘Beauregard’ and I. trifida reference genomes were utilized to identify candidate genes located within 100 kb from the SNPs that may affect the storage traits of dry matter, flesh color, and skin color. These candidate genes include transcription factors (especially Myb, bHLH, and WRKY family members), metabolite transporters, and metabolic enzymes and associated proteins involved in starch, carotenoid, and anthocyanin synthesis. A greater understanding of the genetic loci underlying sweet potato storage root traits will enable marker-assisted breeding of new varieties with desired traits. This study not only reinforces previous research findings on genes associated with dry matter and β-carotene content but also introduces novel genetic loci linked to these traits as well as other root characteristics. Full article

The potential for throttle control of hybrid rocket systems has long been known as a potential advantage for a variety of applications. Because only a single flow path is controlled, theoretically, hybrids should be significantly easier to throttle than bipropellant systems. Unfortunately, the slow response times and nonlinearity of traditional position-control valves have limited practical applications of hybrid throttling. This paper presents an alternative throttling system where the oxidizer flow path is broken into multiple streams, with each flow path controlled by a solenoid-operated on/off valve. The parallel paths allow significantly faster and more precise control than can be achieved using a single position-control valve. The achievable thrust levels are limited only by the size and number of components in the valve cascade. The 8-bit digital throttle system, developed by Utah State University’s Propulsion Research Lab, uses commercial, off-the-shelf components. The throttle system was tested using a 200-N hybrid rocket motor, burning gaseous oxygen, and ABS plastic as propellants. The testing campaign of more than 50 hot fires has demonstrated multiple profiles, including deep throttle ramps, multistep boxcars, and sine waves at frequencies varying from 0.25 to 1-Hz. Comparisons to analytical models are also presented, showing good agreement. Fourier-transform spectra demonstrating the total-system, frequency response are also presented. Full article

Salt rock is considered as an ideal energy storage medium, and compressed air energy storage by a salt cavern can improve the utilisation efficiency of renewable energy. Salt rock in China mostly contains different interlayers, among which mudstone interlayers are the most common. At present, there are relatively few studies on the influence of mudstone interlayers on the long-term stable operation of gas storage. FLAC3D software was used to simulate the long-term operation of salt rock gas storage with different numbers of interlayers in the Yexian area of Pingdingshan. The results show that with the passage of time, the vertical displacement of the surrounding rock of the vertical single-cavity gas storage tank increases gradually. The maximum settlement value at the top of the surrounding rock is always greater than the maximum uplift value at the bottom. The horizontal displacement shows obvious symmetry with the vertical displacement at the top and bottom of the surrounding rock. The effect of the cyclic pressure interval on horizontal displacement is the same as that of vertical displacement. With the increase in the number of interlayers, the volume of the plastic zone gradually increases with the increase in the running time, and the increasing speed shows a growing trend. Full article