Search Results (584)

Green synthesis of copper oxide (CuO) nanoparticles offers a sustainable alternative to conventional chemical methods that often involve toxic reagents and harsh conditions. This study investigates the use of Tithonia diversifolia, an invasive species in Sri Lanka, as a bioreductant for the eco-friendly fabrication of CuO nanoparticles. Using copper sulfate (CuSO₄·5H₂O) as a precursor, eight treatments were conducted by varying precursor concentration, temperature, and reaction time to determine optimal conditions. A visible color change in the reaction mixture initially indicated nanoparticle formation. Among all the conditions, treatment T4 (5 mM CuSO₄, 80 °C, 2 h) yielded the most favorable results in terms of stability, morphology, and crystallinity. UV-Vis spectroscopic analysis confirmed the synthesis, with absorbance peaks between 265 and 285 nm. FTIR analysis revealed organic functional groups and characteristic metal–oxygen vibrations in the fingerprint region (500–650 cm⁻¹), confirming formation. SEM imaging showed that particles were mainly spherical to polygonal, averaging 125–150 nm. However, dynamic light scattering showed larger diameters (~240 nm) due to surface capping agents. Zeta potential values ranged from −16.0 to −28.0 mV, indicating stability. XRD data revealed partial crystallinity with CuO-specific peaks. These findings support the potential of T. diversifolia in green nanoparticle synthesis, suggesting a low-cost, eco-conscious strategy for future applications. Full article

This study investigates the effect of precursor pH (1.3, 2, 4, 6, 8, and 10) on the synthesis of gold nanoparticles (AuNPs) via a green synthesis approach using an aqueous extract of green tea (Camellia sinensis) leaves. The formation of AuNPs was monitored using UV-vis spectrophotometry and confirmed using transmission electron microscopy (TEM). The results confirmed that the morphology and size of the AuNPs are strongly dependent on the pH of the reaction medium. Based on spectral features, the color of the colloids, and TEM analysis, the synthesized samples were classified into three groups. The first (pH 8 and 10) contained predominantly spherical nanoparticles with an average diameter of ~18 nm, the second (pH 1.3 and 2) contained different shaped nanoparticles (20–250 nm in diameter), and the third (pH 4 and 6) contained flower-like nanostructures with a mean diameter of ~60 nm. UV-vis analysis revealed good stability of all AuNP colloids, except at pH 1.3, where a significant decrease in absorbance intensity over time was observed. These findings confirm that tuning the precursor pH allows for controlled manipulation of nanoparticle morphology and stability in green synthesis systems. Full article

Poly(acrylic acid) (PAA) and hydroxypropylcellulose (HPC) hydrogels were synthesized in the absence of a crosslinker. Chemical crosslinking between PAA and HPC was demonstrated through free radical polymerization by a precipitation reaction in acetone as the solvent. These hydrogels exhibited smaller swelling ratios (1 to 5 g H₂O/g) than homo PAA hydrogels synthesized in water as the solvent. They were swollen in a 0.1 M NaOH solution and subsequently used to remove Ni²⁺ ions from aqueous solutions with concentrations ranging from 1000 to 4000 ppm. The absorption capacity of these hydrogels ranged from 91 to 340 mg of Ni²⁺/g in a rapid 1 h process, and from 122 to 435 mg of Ni²⁺/g in a 24 h process, demonstrating an improvement in Ni²⁺ absorption compared to previously reported hydrogels. The colored 1000 and 2000 ppm Ni²⁺ solutions became clear after treatment, while the PAA-HPC hydrogels turned green due to the uptake of Ni²⁺ ions, which were partially chelated by carboxylate groups as nickel polyacrylate and partially precipitated as Ni(OH)₂, resulting in an average absorption efficiency of 80%. The hydrogel was able to release the absorbed Ni²⁺ upon immersion in an HCl solution, with an average release percentage of 76.4%, indicating its potential for reuse. These findings support the use of PAA-HPC hydrogels for cleaning Ni²⁺-polluted water. The cost of producing 1 g of these hydrogels in laboratory conditions is approximately 0.2 USD. Full article

Exploring the mechanisms by which green agricultural production reduces emissions and enhances carbon sequestration in soil can provide a scientific basis for greenhouse gas reduction and sustainable development in farmland. This study uses a combination of meta-analysis and field experiments to evaluate the impact of different agricultural management practices and climatic conditions on soil organic carbon (SOC) and the emissions of CO₂ and CH₄, as well as the role of microorganisms. The results indicate the following: (1) Meta-analysis reveals that the long-term application of organic fertilizers in green agriculture increases SOC at a rate four times higher than that of chemical fertilizers. No-till and straw return practices significantly reduce CO₂ emissions from alkaline soils by 30.7% (p < 0.05). Warm and humid climates in low-altitude regions are more conducive to soil carbon sequestration. (2) Structural equation modeling of plant–microbe–soil carbon interactions shows that plant species diversity (PSD) indirectly affects microbial biomass by influencing organic matter indicators, mineral properties, and physicochemical characteristics, thereby regulating soil carbon sequestration and greenhouse gas emissions. (3) Field experiments conducted in the typical green farming research area of Chenzhuang reveal that soils managed under natural farming absorb CH₄ at a rate three times higher than those under conventional farming, and the stoichiometric ratios of soil enzymes in the former are close to 1. The peak SOC (19.90 g/kg) in the surface soil of Chenzhuang is found near fields cultivated with natural farming measures. This study provides theoretical support and practical guidance for the sustainable development of green agriculture. Full article

It is vital to stabilize pillar dams in underground reservoirs in coal mine goafs to protect groundwater resources and quarry safety, practice green mining, and protect the ecological environment. Considering the actual occurrence of coal pillar dams in underground reservoirs, acoustic emission (AE) mechanical tests were performed on dry, naturally absorbed, and soaked coal samples. According to the mechanical analysis, Quantitative analysis revealed that dry samples exhibited the highest mechanical parameters (peak strength: 12.3 ± 0.8 MPa; elastic modulus: 1.45 ± 0.12 GPa), followed by natural absorption (peak strength: 9.7 ± 0.6 MPa; elastic modulus: 1.02 ± 0.09 GPa), and soaked absorption showed the lowest values (peak strength: 7.2 ± 0.5 MPa; elastic modulus: 0.78 ± 0.07 GPa). The rate of mechanical deterioration increased by ~25% per 1% increase in moisture content. It was identified that the internal crack development presented a macrofracture surface initiating at the sample center and expanding radially outward, and gradually expanding to the edges by adopting AE seismic source localization and the K-means clustering algorithm. Soaked absorption was easier to produce shear cracks than natural absorption, and a higher water content increased the likelihood. The b-value of the AE damage evaluation index based on crack development was negatively correlated with the rock damage state, and the S-value was positively correlated, and both effectively characterized it. The research results can offer reference and guidance for the support design, monitoring, and warning of coal pillar dams in underground reservoirs. (The samples were tested under two moisture conditions: (1) ‘Soaked absorption’—samples fully saturated by immersion in water for 24 h, and (2) ‘Natural absorption’—samples equilibrated at 50% relative humidity and 25 °C for 7 days). Full article

Purpose: The acquirer’s corporate environmental performance (CEP) in mergers and acquisitions has been a subject of debate, yielding mixed results. This paper uses the US firm-level data of 1437 M&A deals from 2002–2019 to examine the impact of overall CEP, resource use, emissions, and innovation on the acquirers’ post-merger market value. Design/methodology/approach: This study employs multi-level fixed effects panel regression using Ordinary Least Squares (OLS) and the instrumental variable (IV) 2SLS method to estimate the models and compare the results with those from robust estimation. Absorbing the multiple levels of fixed effects (i.e., firm, industry, and year) offers a novel and robust algorithm for efficiently accounting for unobserved heterogeneity. The results from IV (2SLS) are more convincing, as the method overcomes the problem of endogeneity due to reverse causality and sample selection bias. Findings: The authors find that CEP has a significant impact on market value, particularly in the long term. While both resource use and emissions performance have positive effects, emissions performance has a stronger impact, presumably because external stakeholders and market participants are more concerned about emissions reduction. The performance of environmental innovation is relatively weak compared to other pillars. Descriptive analysis shows low average scores in environmental innovation compared to the resource use and emissions performance of the acquirers. However, large deals yield significant returns from investing in environmental innovation in both the short and long term compared to small deals. Practical implications: This paper offers several practical implications. First, environmental performance can help improve the acquirer’s long-term market value. Second, managers can focus on the strategic side of environmental performance, based on its pillars, and benchmark their relative position against peers. Third, environmental innovation can be considered a new potential, as the market as a whole in this area is still lagging. Given the growing pressure to improve environmental technology and innovation, prospective acquirers should confidently prioritise actions on green revenue, product innovation, and capital expenditure now rather than ticking these boxes later. Originality value: The key contribution is offering valuable insights into the impact of acquirers’ environmental performance on long-term value creation in mergers and acquisitions (M&A). These results fill the gap in the literature focusing mainly on the effect of environmental pillar and sub-pillar scores on acquirer’s firm value. The authors claim that analysing sub-pillar-level granularity is crucial for accurately measuring the effects on firm-level performance. Full article

We report a passively Q-switched self-Raman laser using a dual-end composite c-cut Nd:YVO₄ crystal, which generates switchable visible emissions at 533 nm, 560 nm, and 589 nm. A Cr⁴⁺:YAG/YAG composite crystal served the role of a saturable absorber to achieve passive Q-switching. An angle-tuned BBO crystal was used to achieve the frequency mixing between the first-tokes wave and the fundamental wave. At an incident pump power of 9.5 W, the maximum average output powers were 425 mW for the 589 nm yellow laser, 193 mW for the 560 nm lime laser, and 605 mW for the 533 nm green laser, with corresponding pulse widths of approximately 3.8, 3.6, and 35.1 ns, respectively. This result shows that a passive Q-switching operation with self-Raman crystals presents a promising approach for compact multi-wavelength pulse laser sources. Full article

Background: Understanding the absorption and distribution of herbicides in plants and animal tissues is essential for assessing their potential risks to human health. Method: In this study, we employed imprint desorption electrospray ionization mass spectrometry imaging (IDESI-MSI) to visualize in both vegetable and animal tissues the absorption of Roundup which is a widely used herbicide. Results: Using IDESI-MSI with a pixel size of 150 µm, we detected the herbicide alongside several endogenous metabolites on oil-absorbing films applied to carrot sections. Time-course experiments revealed progressive herbicide penetration into carrot tissue, with penetration depth increasing linearly over time at a rate of approximately 0.25 mm/h. In contrast, green pepper samples showed minimal herbicide infiltration, likely owing to their hydrophobic cuticle barrier. Additionally, mice fed with herbicide-treated carrots exhibited detectable levels of herbicide in liver and kidney tissues. Conclusions: These findings highlight the utility of IDESI-MSI as a powerful analytical platform for the rapid evaluation of chemical migration and absorption in food and biological systems, with important implications for food safety and toxicological research. Full article

In this work, we propose an automated, real-time optical scanning approach to assessing catalyst performance in the process of nitro-to-amine reduction using well-plate readers to monitor reaction progress. This approach takes advantage of a simple on–off fluorescence probe that gives a shift in absorbance and strong fluorescent signal when the non-fluorescent nitro-moiety is reduced to the amine form. The combination of an affordable probe and a low barrier-to-entry technique provides an accessible approach to high-throughput catalyst screening. Under this paradigm, we screened 114 different catalysts and compared them in terms of reaction completion times, material abundance, price, recoverability, and safety. Using a simple scoring system, we plotted the catalysts in terms of cumulative scores, along with some intentional biases, including an emphasis on preference for catalysts with potential as green catalysts, considering environmental issues and possible geopolitical preferences. Full article

Titanium dioxide (TiO₂) has been widely used as a potential candidate for the production of green hydrogen using the artificial photosynthesis approach. However, the wide bandgap (∼3.3 eV) of anatase TiO₂ makes it difficult to absorb a large fraction of the solar radiation reaching the Earth, thus providing a low photocatalytic activity. Anatase TiO₂ absorbs only 4% of solar radiation, which can be improved by engineering its bandgap to enhance absorption in the visible region. In the literature, many strategies have been adopted to improve the photocatalytic activity of TiO₂, such as metal and non-metal doping and heterojunctions. These techniques have shown incredible enhancement in visible light absorption and improved photocatalytic activity due to their ability to lower the bandgap of pure TiO₂ semiconductors. This review highlights different techniques like doping, heterojunctions, acidic modification, creating oxygen vacancies, and temperature- and pressure-dependence, which have improved the photochemical response of TiO₂ by improving charge-transfer efficiencies. Additionally, the charge-transfer mechanism and enhancement in the photochemical response of TiO₂ is discussed in each portion separately. Full article

Earth materials in construction demonstrate significant potential attributed to their accessibility, recyclability, and low energy demands for processing. Modern techniques have enhanced their mechanical strength and durability, enabling their application in load-bearing and infill walls while preserving ecological benefits. However, existing studies on indoor heat–humidity regulation primarily emphasize material parameters and macro-level performance. Moreover, the dynamic interactions between the unique thermal storage–release mechanisms and indoor environments have not been systematically analyzed. With the Kelvin equation, capillary mechanics, adsorption theories, and microstructural analysis were integrated in this study to quantify cyclic capillary condensation and evaporation in microvoids. The results reveal that earth materials contain abundant medium-sized pores (19.85–53.83 nm) sustaining vapor exchange with their surroundings. Capillary condensation occurs 0.86–0.96 times the planar surface vapor pressure, influenced by pore size (negatively correlated) and temperature (negatively correlated). During the daytime, capillary evaporation occurs in the nanopores of the raw earth wall under the influence of the outdoor environment’s cyclical temperature and humidity. This process absorbs heat from the indoor environment and raises the ambient humidity. During the nighttime, capillary condensation occurs in the pores, releasing heat to the indoor area and absorbing moisture from the environment, contributing to the balance of the indoor thermal environment of the earth buildings. The findings lay a scientific foundation for quantitatively evaluating earth buildings’ indoor climate control performance, supporting their integration into green building systems. This research bridges knowledge gaps in micro-to-macro thermal dynamics while advancing the ecological optimization of materials for sustainable architecture. Full article

Satureja montana L. (winter savory, family Lamiaceae) is an aromatic herb that is widespread throughout the Mediterranean region. In a prior study, the optimization of the green hydroxypropyl-β-cyclodextrin (HP-β-CD)-glycerol-assisted extraction procedure of S. montana was performed. As a result, four extracts abundant in total phenols (OPT-TP), total phenolic acids including rosmarinic acid (OPT-TPA-RA), total flavonoids (OPT-TF), and luteolin derivatives (OPT-LG) showing anti-elastase and anti-hyaluronidase properties, were prepared. Subsequently, we further explored the phytochemical, dermatological, and cosmeceutical potentials of these extracts, evaluating their antioxidant, anti-inflammatory, anti-tyrosinase, and anti-ultraviolet (UV) absorption activities. Furthermore, the biocompatibility of the extracts and their wound-healing properties were assessed using HaCaT cells. The results indicate that the extracts exhibited excellent antioxidant and cosmeceutical activities, which surpassed the activities of the employed standards in several assays (DPPH antiradical activity, β-carotene-linoleic acid, anti-lipoxygenase, anti-heat-induced ovalbumin coagulation, and UV absorbance assays). Furthermore, the extracts preserved more than 80% of the HaCaT cell viability at concentrations up to 62.5 µL extract/mL and also enhanced wound healing in the in vitro scratch wound-healing model. For example, the application of OPT-TP and OPT-TF led to 48.6% ± 3.3% and 48.6% ± 5.4% wound closure, respectively, after 48 h, compared to 34.8% ± 2.3% in the control group. The extracts exhibited excellent bioactivities, making them promising candidates for the development of cosmeceutical products, while their high biocompatibility indicates that they are suitable for direct application in cosmetics without prior solvent removal. Full article

Artificial photoelectric synapses exhibit great potential for overcoming the Von Neumann bottleneck in computational systems. All-inorganic halide perovskites hold considerable promise in photoelectric synapses due to their superior photon-harvesting efficiency. In this study, a novel wavy-structured CsPbBr₃/ZnO hybrid film was realized by depositing zinc oxide (ZnO) onto island-like CsPbBr₃ film via atomic layer deposition (ALD) at 70 °C. Due to the capability of ALD to grow high-quality films over small surface areas, dense and thin ZnO film filled the gaps between the island-shaped CsPbBr₃ grains, thereby enabling reduced light-absorption losses and efficient charge transport between the CsPbBr₃ light absorber and the ZnO electron-transport layer. This ZnO/island-like CsPbBr₃ hybrid synaptic transistor could operate at a drain-source voltage of 1.0 V and a gate-source voltage of 0 V triggered by green light (500 nm) pulses with low light intensities of 0.035 mW/cm². The device exhibited a quiescent current of ~0.5 nA. Notably, after patterning, it achieved a significantly reduced off-state current of 10⁻¹¹ A and decreased the quiescent current to 0.02 nA. In addition, this transistor was able to mimic fundamental synaptic behaviors, including excitatory postsynaptic currents (EPSCs), paired-pulse facilitation (PPF), short-term to long-term plasticity (STP to LTP) transitions, and learning-experience behaviors. This straightforward strategy demonstrates the possibility of utilizing neuromorphic synaptic device applications under low voltage and weak light conditions. Full article

In view of the growing interest in green building transitions (GBTs) over the past decade, various GBT frameworks have been developed. Concurrently, a comprehensive systematic review of GBT research is yet to be conducted, leaving ambiguity surrounding the evolution and adoption of diverse models in this field. In general, existing frameworks mainly adopt socio-technical or socio-institutional approaches. Focusing on different individual practices, these studies have resulted in fragmented results. There is a lack of an integrative understanding of the socio-ecology of the GBT system. Hence, this study aims to consolidate existing research works conducted in the GBT fields and develop an integrative GBT framework towards a socio-ecological approach. A mixed-methods approach was employed, combining qualitative content analysis with quantitative bibliometric methods. The findings indicated that qualitative approaches (constituting 47%, encompassing 34 articles) and modeling techniques (comprising 37%, amounting to 27 articles) emerged as the predominant research methodologies employed. Evolutionary game theory and the multi-level perspective stood out as the most prevalent theoretical frameworks utilized in studies of GBT. Noteworthy contributions to the field were observed from China (with 29 articles) and the UK (with 17 articles). Notable keywords such as “barriers” (frequency = 16) and “energy” (frequency = 11) were identified as pivotal in the analysis. Furthermore, a total of ten co-occurrence clusters were identified to classify related keywords, enhancing content relevance and pinpointing key thematic groupings. The findings highlighted the need for a new direction in future GBT research, specifically focusing on the socio-ecological perspective. This perspective not only focuses on the human dimension of technical and institutional factors but also on the exchange between the ecosystem and society. It also emphasizes the resilience and adaptability to absorb disruptions and progress towards a more desired system state. This study offers valuable contributions to the existing body of GBT literature and has implications for researchers and research institutions in this field. Full article

Urban microclimates, which include phenomena such as urban heat islands (UHIs) as well as cooler environments created by shaded areas and green spaces, significantly affect social behavior and contribute to varying levels of social isolation in cities. UHIs, driven by heat-absorbing materials like concrete and asphalt, can increase urban temperatures by up to 12 °C, discouraging outdoor activities, especially among vulnerable populations like the elderly and those with chronic health conditions. In contrast, shaded areas and green spaces, where temperatures can be 2–5 °C cooler, encourage outdoor engagement and foster social interaction. This narrative review aims to synthesize current literature on the relationship between urban microclimates and social isolation, focusing on how UHIs and shaded areas influence social engagement. A comprehensive literature review was conducted, selecting sources based on their relevance to the effects of localized climate variations on social behavior, access to green spaces, and the impact of urban design interventions. A total of 142 articles were initially identified, with 103 included in the final review after applying inclusion/exclusion criteria. Key studies from diverse geographical and cultural contexts were analyzed to understand the interplay between environmental conditions and social cohesion. The review found that UHIs exacerbate social isolation by reducing outdoor activities, particularly for vulnerable groups such as the elderly and individuals with chronic health issues. In contrast, shaded areas and green spaces significantly mitigate isolation, with evidence showing that in specific study locations such as urban parks in Copenhagen and Melbourne, such areas increase outdoor social interactions by up to 25%, reduce stress, and enhance community cohesion. Urban planners and policymakers should prioritize integrating shaded areas and green spaces in city designs to mitigate the negative effects of UHIs. These interventions are critical for promoting social resilience, reducing isolation, and fostering connected, climate-adaptive communities. Future research should focus on longitudinal studies and the application of smart technologies such as IoT sensors and urban monitoring systems to track the social benefits of microclimate interventions. Full article