Search Results (206)

We theoretically study the single ionization of liquid water by impact of fast electrons. A realistic description of the wavefunction for an isolated water molecule in the liquid phase is obtained by means of a Wannier orbital formalism. In this way, we consider ionization from the most external orbitals 1B₁, 2A₁, 1B₂ and 1A₁ of a single liquid water molecule. Triple, double, single differential and total cross sections are computed through a first order model with proper Coulomb conditions for the ionized electron. We compare our calculations with measurements and other theoretical results for liquid and gaseous phases. An analysis of the main features of the cross sections is performed. Previous theoretical works found almost no discrepancies between these observables in spite of the physical dissimilarities of both phases. In this work, we compare our results with other theories and with the available experiments for vapor. We report interesting differences between the differential and total cross sections of the mentioned phases. Full article

This paper reports a novel effort to estimate and evaluate the coefficients of Hg transfer across the water/air interface in lakes such as Cane Creek Lake (CCL, Cookeville, TN, USA). This was accomplished by calculating the coefficients (k_w) using the Two-Thin Film (TTF) Model for Hg transfer together with the field-measured data of Hg emission flux (F), dissolved gaseous mercury concentration (DGM), air Hg concentration (C_a), and water temperature for Henry’s coefficient (K_H) obtained from a separate field study at the CCL. The daily mean k_w values range from 0.045 to 0.21 m h⁻¹, with the min. at 0.0025–0.14 and the max. at 0.079–0.41 m h⁻¹, generally higher for the summer, and from 0.0092 to 0.15, with the min. at 0.0032–0.033 and the max. at 0.017–0.31 m h⁻¹, generally lower for the fall and winter, exhibiting an apparent seasonal trend. The highest k_w values occur in August (mean: 0.21, max.: 0.41 m h⁻¹). Our k_w results add to and enrich the aquatic interfacial Hg transfer coefficient database and provide an alternative avenue to evaluate and select the coefficients for the TTF Model’s application. The k_w results are of value in gaining insights into the Hg transfer actually occurring across the water/air interface under environmental influences (e.g., wind/wave, solar radiation). Our k_w results do not show a clear, consistent correlation of k_w with wind/wave effect, nor sunlight effect, in spite of some correlations in sporadic cases. Generally, the k_w values do not exbibit the trends prescribed by the model sensitivity study. The comparisons of our k_w results with those obtained using wind-based transfer models (the Liss/Merlivat Model, the Wanninkhof Model, and the modified linear model) show that they depart from each other. The findings of this study indicate that the TTF Model has limitations and weaknesses. One major assumption of the TTF Model is the equilibrium of the Hg distribution between the air and water films across the water/air interface. The predominant oversaturation of DGM shown by our DGM data evidently challenges this assumption. This study suggests that aquatic interfacial Hg transfer is considerably more complicated, involving a group of factors, more than just wind and wave. Full article

The dynamic relationship between microplastics (MPs) in the air and on the Earth’s surface involves both natural and anthropogenic forces. MPs are transported from the ocean to the air by bubble scavenging and sea spray formation and are released from land sources by air movements and human activities. Up to 8.6 megatons of MPs per year have been estimated to be in air above the oceans. They are distributed by wind, water and fomites and returned to the Earth’s surface via rainfall and passive deposition, but can escape to the stratosphere, where they may exist for months. Anthropogenic sprays, such as paints, agrochemicals, personal care and cosmetic products, and domestic and industrial procedures (e.g., air conditioning, vacuuming and washing, waste disposal, manufacture of plastic-containing objects) add directly to the airborne MP load, which is higher in internal than external air. Atmospheric MPs are less researched than those on land and in water, but, in spite of the major problem of a lack of standard methods for determining MP levels, the clothing industry is commonly considered the main contributor to the external air pool, while furnishing fabrics, artificial ventilation devices and the presence and movement of human beings are the main source of indoor MPs. The majority of airborne plastic particles are fibers and fragments; air currents enable them to reach remote environments, potentially traveling thousands of kilometers through the air, before being deposited in various forms of precipitation (rain, snow or “dust”). The increasing preoccupation of the populace and greater attention being paid to industrial ecology may help to reduce the concentration and spread of MPs and nanoparticles (plastic particles of less than 100 nm) from domestic and industrial activities in the future. Full article

Rice milling in Sub-Saharan Africa (SSA) remains highly dependent on water availability and favorable weather conditions, making local millers vulnerable to water- and weather-related pressures (WWrP). This study examines how rice millers in Makurdi and Adikpo, Benue State, Nigeria, adapt to these pressures. Data were collected through snowball sampling involving 21 rice millers and two workshops attended by 14 millers. Content and thematic analyses of data were carried out using NVivo 11. Findings indicate that rice milling operations are highly exposed and sensitive to flooding, excessive wetness, dryness, high humidity, and water scarcity. These pressures are likely to intensify due to climate change and pronounced climate variability. To adapt, millers employ endogenous strategies, including temporarily relocating or evacuating mills, rotating drying schedules, modifying drying methods, reducing or suspending parboiling during floods, and digging wells. In spite of these adaptation measures, locally milled rice continues to face issues of poor quality and diminished competitiveness. Consequently, this study highlights upgrading milling technologies and infrastructure, promoting proactive and long-term adaptation measures, and supporting collective adaptation strategies among millers to enhance resilience in the rice value chain. Full article

The formation of microbial colonies and biofilms are common on dental restorations. This can lead to secondary caries. Another common complication is the post-operative inflammation noted in patients. The traditionally used dental composites are designed without the inherent components having antimicrobial and inflammatory properties. This has become a major challenge in current restorative dentistry applications. In order to address these challenges, a possible approach is to incorporate eugenol nanoparticles (NPs) into dental composites. This approach can offer dual therapeutic benefits since eugenol possess both antimicrobial and inflammatory properties. In fact, compared to synthetic antimicrobial agents, eugenol exhibits antibacterial activity not only against Streptococcus mutans but also against a range of oral pathogens. It also exhibits anti-inflammatory effects that can promote healing by reducing post-operative sensitivity. In spite of the above benefits, eugenol cannot be incorporated directly into dental materials. This is because eugenol is highly volatile and has poor water solubility. The encapsulation of eugenol in suitable nano-materials can overcome these limitations. In addition, it can enable the controlled and sustained release of desirable agents for long-term therapeutic action. In this review, we explore the mechanisms, advantages and potential clinical applications of dental composites containing NP integrated with eugenol. We highlight the advantages of having antimicrobial and anti-inflammatory functions in a single restorative material. At the same time, we acknowledge the need for more in-depth research to optimize NP formulations with eugenol that does not compromise the mechanical properties of dental materials. Based on a thorough literature review, we believe that this approach has much potential in restorative dentistry procedures that will aid therapeutic outcomes in the future. Full article

Although intensive farming practices have greatly increased food production, they have undermined the soil ecosystem services on which agriculture depends. Biochar application in soils is increasingly gaining worldwide acceptance as a means of addressing these environmental challenges while enhancing agricultural productivity. Biochar offers dual benefits that support food security and ecological well-being through enhanced soil fertility and plant nutrition. These benefits include water retention, promotion of soil microbial functioning, carbon sequestration, and nutrient absorption, among others. In spite of these known benefits, many studies continue to emphasize the roles biochar plays in enhancing soil health and crop yields but often neglect the influence of biochar characteristics, which are key in optimizing these soil ecosystem services. Thus, it is important to understand how biochar characteristics influence soil in supporting, regulating, and provisioning ecosystem services. This review offers a comprehensive and integrative assessment on how biochar’s characteristics influence key soil ecosystem services rather than examining each service individually. The focus is on how biochar feedstock material and pyrolysis temperature determine the characteristics of generated biochar and how these characteristics influence biochar’s efficacy in supplying soil ecosystem services and nutrient dynamics for enhanced crop yields. Full article

A shape memory alloy with the chemical composition Fe-14Mn-6Si-9Cr-5Ni (mass %) was produced by powder metallurgy (PM) from as-blended powders mixed with mechanically alloyed (MA’ed) powder volumes in amounts of 0, 10 and 20. After powder blending, pressing and sintering, the specimens were hot-rolled, spark erosion cut with different configurations and solution-treated between 700 and 1100 °C. After metallographic preparation, structural analyses were performed by X-ray diffraction and microscopic observation performed by optical and scanning electron microscopy (SEM). The analyses revealed the presence of thermal- and stress-induced martensites caused by solution treatment and pre-straining. Due to the relatively low Mn amount, significant quantities of α′ body center cubic martensite were formed during post-solution treatment water cooling. Solution-treated lamellar specimens underwent a training thermomechanical treatment comprising repeated cycles of room temperature bending, heating and sputtered water cooling. By cinematographic analysis, the occurrence of the shape memory effect (SME) was revealed, in spite of the large amount of α′ bcc martensite. Tensile specimens were subjected to room temperature failure tests and pre-straining (up to 4% permanent strain, after loading–unloading). After tensile pre-straining, a diminution of α′ martensite amount was noticed on XRD patterns, which was associated with the formation of internal sub-bands in the substructure of martensite and were observed by high-resolution SEM. These results prove that SME can be obtained in trained PM_MA’ed Fe-14Mn-6Si-9Cr-5Ni specimens in spite of the large amount of thermally induced α′ bcc martensite, the stress-induced formation of which is impeded by the presence of internal sub-bands. Full article

Linden (Tilia) is one of the most frequently utilized plants for the preparation of infusions because of its salutary effects, including the reduction in inflammatory processes and pain, alleviation of stress, and lowering of blood pressure. As Linden is a common species in Bulgarian cities, it is frequently used for homemade infusions. The regular consumption of these tea beverages may contribute to the attainment of the recommended daily allowances of certain minerals, but it may also result in the accumulation of toxic elements within the human body. The present study compares the concentrations of essential and toxic elements in linden blossom collected from disparate locations in Plovdiv, Bulgaria, with those of samples gathered in ecologically pristine regions and commercially available products labeled “bio”. Both total element content and extractable forms in infusions were quantified by ICP-MS. The health risk due to consuming infusions was assessed by comparing the water, tea, drinks, and EFSA regulations. The applied cluster analysis divided the samples from the urban area into three groups related to traffic pollution. In spite of the short blooming period, the concentrations of Al, Fe, Pb, V, Cr, Co, Ni, and Cd in the samples from the most polluted areas are increased by a factor of two compared to those from the clean zones. Full article

The integration of the Crop Growth Model (CGM), Radiative Transfer Model (RTM), and Machine Learning Algorithm (MLA) for estimating crop traits represents a cutting-edge area of research. This integration requires in-depth study to address RTM limitations, particularly of similar spectral responses from multiple input combinations. This study proposes the integration of CGM and RTM for crop trait retrieval and evaluates the performance of CGM output-based RTM spectra generation for multiple crop traits estimation without biased sampling using machine learning models. Moreover, PROSAIL spectra as training against Harmonized Landsat Sentinel-2 (HLS) as testing was also compared with HLS data only as an alternative. It was found that satellite data (HLS, 80:20) not only consistently performed better, but PROSAIL (train) and HLS (test) also had satisfactory results for multiple crop traits from uniform training samples in spite of differences in simulated and real data. PROSAIL-HLS has an RMSE of 0.67 for leaf area index (LAI), 5.66 µg/cm² for chlorophyll ab (Cab), 0.0003 g/cm² for dry matter content (Cm), and 0.002 g/cm² for leaf water content (Cw) against the HLS only, with an RMSE of 0.40 for LAI, 3.28 µg/cm² for Cab, 0.0002 g/cm² for Cm, and 0.001 g/cm² for Cw. Optimized machine learning models, namely Extreme Gradient Boost (XGBoost) for LAI, Support Vector Machine (SVM) for Cab, and Random Forest (RF) for Cm and Cw, were deployed for temporal mapping of traits to be used for wheat productivity enhancement. Full article

CuM and AgM (M = Cr, Fe) catalysts were synthesized, characterized, and evaluated in methane reforming with CO₂ with and without pretreatment under a H₂ atmosphere. Their textural and structural characteristics were evaluated using various physicochemical methods, including XRD, B.E.T., SEM-EDS, XPS, and H₂-TPR. It was shown that the nature of the species has a significant effect on these structural, textural, and reactivity properties. AgCr catalysts, presenting several oxidation states (Ag⁰, Ag⁺¹, Cr³⁺, and Cr⁶⁺ in Ag, AgCrO₂, and AgCr₂O₄), showed the most interesting catalytic performance in their composition. The intermediate Cr₂O₃ phase, formed during the catalytic reaction, played an important role as a catalytic precursor in the in situ production of highly dispersed nanoparticles, being less prone to coke formation in spite of the severe reaction conditions. In contrast, the AgFe catalyst showed low activity and a low selectivity for DRM in the explored temperature range, due to a significant contribution of the reverse water–gas shift reaction, which accounted for the low H₂/CO ratios. Full article

A purposely naïve and semi-empirical model allows for the reproduction of the phenomenological behavior of any real microbial culture by adjusting the values of three parameters, which have a biological meaning only for a virtual microbial culture that mimics the behavior of the real ones. Any genomic, biochemical, and physical peculiarity (microbial species, physiological condition, pH, water activity, temperature, etc.) that distinguishes one real culture from another is “translated” to an effect of the degree of progress of the population density and cell age in the virtual culture. The model leads to a self-consistent description of the growth curve, which looks like the result of an autocorrelation effect. This explains why, in spite of genomic and physiologic differences, all the growth curves show a sigmoid trend. The traditional growth curve and the subsequent exponential decay in the log(N)-vs-t plot can be replaced by straight-line trends when referring to the degree of progress of the population density of the virtual culture. Full article

The term “sustainable urbanism” has been criticized over its inconsistent and imprecise definition, leading to challenges in implementing actionable reforms and achieving urban sustainability goals. A clearer approach may be to identify its opposite: specifically, forms of urbanism that cause an unacceptable buildup of toxic or climate-altering emissions, deplete resources beyond sustainable levels, progressively destroy critical ecologies, and cause other identifiable sources of potentially catastrophic harm to human and urban welfare. Here, we present a model of such an “unsustainable urbanism”, and we further observe that it is in fact the dominant model of urban structure to this day. Its features include an over-reliance on low-occupancy vehicular transport, at the expense of other modes including walking; inefficient envelope, size, orientation and adaptability of buildings; ecologically destructive infrastructure systems for handling water, energy and other resources; and—under-appreciated but fundamentally important, as we will explore—the decline of a well-connected, walkable, functionally and aesthetically appealing public realm. This model remains dominant in spite of the many goals, agendas and declarations on sustainable urbanism at the highest policy level. We observe that the lack of progress is in large part the result of system “lock-in”—economic and professional incentives and disincentives, standards, laws, codes, and other forms of feedback that reinforce “business as usual” and create barriers to reform. Therefore, the agenda ahead must address the specific levers of change to overcome this systemic lock-in, drawing insights from economics, technology and the social sciences to do so. We present the outlines of this agenda and make conclusions for the necessary steps ahead. Full article

Freshwater is a limited resource that is needed by all living things. However, the available amount of it cannot counterbalance the explosion of the human population in recent years. This condition is worsened because of the contamination of many bodies of water by industrialization and urbanization. Nanomaterials offer an alternative sustainable solution due to their unique size-dependent properties, i.e., high specific surface area and discontinuous properties. These advantages can be utilized to reuse wastewater to become a sustainable water source for drinking water. Many recent studies have proven that nanotechnologies in the forms of nano-adsorbents, nanomembranes, and nano-catalysts have high performances in water contaminants removal. This review provides a comprehensive discussion around these nanotechnologies from the mechanism, applications, efficacy, advantages, disadvantages, and challenges in applications for producing drinking water including by wastewater reusing. Each nanotechnology reviewed here has been proven to perform effectively for water contaminants removal in laboratory scale. An initial study is also performed in this review to analyze the sustainability of nanotechnology for producing drinking water. In spite of the great efficacy, nanotechnologies utilization in commercial scales is still limited which requires further studies. Full article

In spite of the demonstrated efficacy of basalt stone powder as a cost-effective and readily available additive in enhancing the mechanical properties and durability of ordinary-weight concrete, its application in Structural Lightweight Concrete (SLWC) remains unexplored. This study introduced a mixing design for SLWC incorporating Light Expanded Clay Aggregates (LECAs) and basalt stone powder with a subsequent evaluation of its strength and durability characteristics. The experimental procedure involved creating various samples, considering differing proportions of cement, water, basalt stone powder, sand, LECA, superplasticizer, and aerating agent. The compressive strength and density of the 28-day-cured concrete specimens were determined. An optimal SLWC with a compressive strength of 42 MPa and a density of 1715 kg/m³ was identified. The flexural and tensile strength of the optimal SLWC exceeded those of ordinary-weight concrete by 6% and 3%, respectively. Further evaluation revealed that the optimal SLWC exhibited 1.46% water absorption and an electrical resistivity of 139.8 Ohm.m. Notably, the high porosity of LECA contributed to the low durability of SLWC. To address this, cost-effective external coatings of emulsion and fiberglass were applied to enhance the durability of the SLWC. Four coating scenarios, including one-layer bitumen, two-layer bitumen, three-layer bitumen, and three-layer bitumen with fiberglass, were investigated. The measurements of electrical resistance and compressive strength revealed that the use of three layers of emulsion bitumen and fiberglass improved the durability of the concrete by over 90% when the SLWC was exposed to severe chloride attack. Consequently, the durability of the SLWC with an external coating surpassed that of ordinary-weight concrete. Full article

The cooling potential of tree species in Central European cities is insufficiently studied during extreme heat and drought, although a stronger surge in heatwaves compared to the global average is observed in this region. Remote sensing-based thermal surveys are an important tool to shed light on the mitigation effects of green infrastructure, but approaches covering extreme events are scarce. In this study, we present a simple, low-cost thermal airborne methodology that covers the current daily heat record in 2022, after the second warmest and third driest spring-to-summer period since 1949, in the medium-sized German city of Forchheim. We found that in spite of record-breaking heat and drought conditions, trees still had a considerable cooling potential with surface temperatures of 2 °C to 6 °C below air temperatures. Tree species were characterized by substantial median differences in tree surface temperatures up to 3.64 °C. Conifers and drought-sensitive broadleaf species showed the highest temperatures during the extreme event, while riparian species with potentially good water provision showed the highest cooling potential. In addition to tree species, imperviousness and tree NDVI were important variables for urban tree surface temperature, showing positive (imperviousness) and negative (NDVI) correlations with tree surface temperatures. Our study provides a methodological remote sensing example for the spontaneous and rapid coverage of extreme events, documenting the benefits of tree species in the urban context. Full article