Search Results (133)

Background: The observed abundance ratios of alkali species in ground-based spectra of comets deviate from solar composition, suggesting alkali ejection from phenoxides reacting with carbon dioxide at the nucleus surface (alkali-phenoxide carbonylation). Methods: Here, we search for the alkali emissions in spectra of the coma and of the trail of Comet C/2023 A3 (Tsuchinshan-ATLAS) exploiting the double-fiber entrance of the high-resolution PEPSI spectrograph at the 8.4 m Large Binocular Telescope. Results: Spectra sampling the nucleus yield $Na/K$ ratios 3.6 times higher than the chondritic value, and even higher ratios sampling the trail. This fact excludes photodesorption as the main sodium source, leaving sodium-phenoxide carbonylation at the surface of the main nucleus and the trail mininuclei as the primary sodium source. Conclusions: The nucleus temperature and the faint KI line exclude potassium-phenoxide carbonylation. For the first time, KI is detected in the trail of an Oort cloud comet, suggesting potassium photodesorbed from the trail mininuclei. Sodium-phenoxide carbonylation is at least six times more efficient than sodium photodesorption if the $Na/K$ ratio in the C/2023 A3 nuclei is chondritic. Trails composed of sub-km-sized mininuclei may be common features of Oort cloud comets. Full article

A new selective fluorescent probe based on a vitamin B₆ derived hydrazone was synthesized and characterized for the detection of Al³⁺ and Ga³⁺ ions. The probe’s selectivity and sensitivity were evaluated using UV-Vis, fluorescence, and NMR spectroscopy in a buffered DMSO/water solution, complemented by density functional theory (DFT) calculations to elucidate the electronic structure and coordination modes of the resulting complexes. The probe exhibited a notable “turn-on” fluorescence response upon binding Al³⁺ and Ga³⁺, with emission maxima at 466 nm and 477 nm, respectively, and detection limits as low as 48 nM for Al³⁺ and 33 nM for Ga³⁺. The probe showed high selectivity for these ions over a wide range of competing cations and anions, forming stable 1:1 complexes with log β′ values of 5.98 for Al³⁺ and 6.28 for Ga³⁺. DFT calculations revealed a tridentate coordination mode via the phenolic oxygen, azomethine nitrogen, and carbonyl oxygen, with distinct electronic transitions for each complex, including a ligand-to-metal charge transfer character in the Ga³⁺ complex. The probe demonstrates reversibility and excellent solution stability, offering a simple and sensitive platform for the environmental and biological monitoring of aluminum(III) and gallium(III) ions. Full article

Thermal modification is widely applied to improve the durability and dimensional stability of wood; however, it alters the emission profile of volatile organic compounds (VOCs), which may affect indoor air quality. This study evaluated the effect of accelerated aging on VOC emissions from thermally modified Norway spruce (Picea abies) wood. Untreated and thermally treated samples (160, 180, and 210 °C) were subjected to accelerated aging in a xenon test chamber for 600 h. VOC emissions were analyzed using headspace gas chromatography–mass spectrometry (HS-GC-MS), and total VOC emissions (TVOC) were calculated from peak areas. Thermal modification significantly reduced TVOC compared to untreated wood, with samples treated at 210 °C showing up to a 376-fold decrease. Increasing modification temperature reduced the amount and variability of emitted VOCs and altered their chemical composition. Terpenes dominated in untreated wood, particularly α-pinene (51%), whereas thermally treated samples showed lower terpene content and higher proportions of carbonyl compounds such as furfural. Accelerated aging further affected VOC emissions, including a 42% decrease in TVOC for the 160 °C sample and compositional shifts characterized by the disappearance or formation of specific compounds. Thermal modification and subsequent aging substantially modify VOC emission profiles and improve emission stability of thermally treated spruce wood. Full article

This study investigates the material recycling potential of discarded wind instrument reeds (Arundo donax), which are conventionally incinerated, by compounding them with thermoplastics (thermoplastic polyolefin, TPO; polybutylene succinate, PBS). After recovered reeds were pulverized and injection-molded at 10 and 30 wt% concentrations, their mechanical and interfacial properties were evaluated. Experimentally obtained results indicate that waste reeds function as effective reinforcing agents, particularly when combined with biodegradable PBS. Incorporating 30 wt% reed flour into PBS enhanced flexural strength by approximately 1.7 times and flexural modulus by 2.8 times compared to the neat resin. This superior performance relative to TPO composites is attributed to robust interfacial hydrogen bonding among PBS carbonyl groups and the hydroxyl groups on the reed surface. Additionally, thermal and spectroscopic analyses revealed that these strong interactions elevate the crystallization temperature and generate a “Rigid Amorphous Phase” (RAF) that facilitates efficient stress transfer. These research findings demonstrate the feasibility of creating high-quality, bio-based composites, offering a sustainable method to reduce petroleum reliance and carbon dioxide emissions by upcycling musical waste. Full article

Zinc oxide (ZnO) nanostructures suffer from fast electron–hole recombination, limiting their applicability in photocatalytic environmental remediation, and carbon additives such as detonation nanodiamonds (DNDs) are constrained by their high defect density. To address this, ZnO nanocomposites modified with high-pressure, high-temperature nanodiamonds (HPHT NDs) were synthesized to evaluate whether their intrinsically lower defect density—evidenced by a dominant diamond Raman peak at 1330 cm⁻¹ and a low sp² carbon fraction of 6.6% compared to oxidized DNDs with strong D/G bands (~1350/1580 cm⁻¹) and ~25–35% sp² carbon—can enhance charge separation and improve photocatalytic activity. Oxidized HPHT NDs bearing carbonyl, carboxyl, and hydroxyl groups enabled covalent attachment to ZnO, and the resulting ND–ZnO composites were characterized by SEM/EDX, ATR-FTIR, Raman spectroscopy, XPS, and cathodoluminescence (CL). EDX confirmed increasing carbon incorporation from 13.0 to 52.9 at.%, while XPS revealed a 0.5 eV shift in the Zn 2p₃/₂ peak and an increase in Zn–O–Zn lattice oxygen from 31.3% to 61.6% in ND–ZnO 10. CL showed enhanced near-band-edge emission and reduced Zni-related luminescence (~3.0 eV). ND–ZnO 10 achieved a nearly threefold-higher degradation rate constant (0.0251 min⁻¹) than pristine ZnO (0.0087 min⁻¹) and retained 88% efficiency after five cycles, demonstrating strong potential for durable wastewater treatment. Full article

Based on continuous field observations conducted at the Shangdianzi Regional Atmospheric Background Station from 21 October to 20 November 2024 and from 1 December 2024, to 2 January 2025, this study systematically analyzed the concentration levels, seasonal variations, diurnal patterns, and ozone formation potential (OFP) of 24 carbonyl compounds (OVOCs) in the atmosphere during autumn and winter. Source apportionment was further investigated using characteristic ratios, correlation analysis, and multiple linear regression. The results indicate that the average concentration of Σ24OVOCs during the observation period was 2.70 ± 1.55 ppb. Formaldehyde, acetone, and acetaldehyde were the dominant species, accounting for 94.5% of the total concentration in this background area. A significant seasonal difference in carbonyl concentrations was observed, with the average concentration in autumn (3.68 ± 1.66 ppb) being approximately 2.1 times higher than that in winter (1.78 ± 0.58 ppb). The diurnal variation in most carbonyls exhibited a pattern of nighttime accumulation and daytime depletion, which was consistent with the trend of NO₂. The OFP results show that the average OFP of Σ24OVOCs was 30 ± 16 μg/m³, with formaldehyde contributing 86.9%, identifying it as a key precursor for ozone formation in the background region. Source analysis revealed that carbonyl compounds in autumn were influenced by combined natural, vehicular, and industrial sources, with significant secondary formation (27–36%) observed for C2 (acetaldehyde) and C3 (mainly acetone and propanal) species. In winter, anthropogenic contributions to carbonyls increased, with C2 and C3 species primarily originating from combustion sources, vehicle emissions, and industrial releases. This study provides the first insights into the pollution characteristics and source profiles of carbonyl compounds during autumn and winter at the Shangdianzi background site, offering a scientific basis for understanding regional atmospheric oxidative capacity and formulating integrated air pollution control strategies. Full article

Pesticide residues from agriculture pose persistent threats to ecosystems and human health. Precipitation and surface runoff facilitate the transport of pesticide residues, leading to their subsequent accumulation in lakes and rivers. Microalgae-based bioremediation offers a promising and environmentally friendly approach for degrading and detoxifying these residues. This study employed liquid chromatography–mass spectrometry (LC-MS) to determine pesticide residues in various microalgal solutions. Using three-dimensional excitation-emission matrix (3D-EEM) spectroscopy and fluorescence regional integration (FRI), we quantified the dynamics of dissolved organic matter (DOM) and its relationship with pesticide degradation in the microalgal system. Over time, Tolypothrix tenuis exhibited the highest degradation rate for THX (95.7%), while Anabaena showed the most effective degradation for ATZ (53.8%). Based on structural analysis of degradation products, three potential degradation pathways for THX and ATZ under microalgae action were proposed. Moreover, the degradation process may also involve reactive oxygen species and intracellular enzymes. Hydroxylation and carboxylation were the primary reactions involved in THX degradation, leading to ring opening and subsequent mineralization. In ATZ, the initially removed groups included methyl and carbonyl groups, with the final products undergoing hydroxylation and subsequent mineralization to water and carbon dioxide. This study, conducted within the context of aquatic environmental protection, investigates the threat of pesticide residues to aquatic ecosystems. It further elucidates the associated environmental impacts and degradation mechanisms from a microalgal perspective. Full article

VOCs are significant precursors for the formation of O₃ and SOA, directly impacting human health. This study employs multiple approaches to analyzing atmospheric VOCs by focusing on OVOCs including aldehydes, ketones, and phenols, with a case study in Beijing, China. We analyzed the concentration levels and compositions of VOCs and their atmospheric activities, offering a new perspective on VOCs. This analysis was conducted through offline measurements of volatile phenols and carbonyl compounds, complemented by online VOC observations during the summer period of high O₃ levels. The total atmospheric VOCs concentration was found to be 51.29 ± 10.01 ppbv, with phenols contributing the most (38.87 ± 11.57%), followed by carbonyls (34.91 ± 6.85%), and aromatics (2.70 ± 1.03%, each compound is assigned to only one category based on its primary functional group, with no double counting). Carbonyls were the largest contributors to the OFP at 59.03 ± 14.69%, followed by phenols (19.94 ± 4.27%). The contribution of phenols to the SOAFP (43.37 ± 9.53%) and the L_OH (67.74 ± 16.72%) is dominant. Among all quantified VOC species, phenol and formaldehyde exhibited the highest species-level contributions to atmospheric reactivity metrics, including L_OH, OFP and SOAFP, owing to their combination of elevated concentrations and large kinetic or MIR coefficients. Using the PMF model for source analysis, six main sources of volatile organic compounds were identified. Solvent use and organic chemicals production were found to be the primary contributors, accounting for 31.76% of the total VOCs emissions, followed by diesel vehicle exhaust (17.80%) and biogenic sources (15.51%). This study introduces important OVOCs such as phenols, re-evaluates the importance of OVOCs and their role in atmospheric chemical processes, and provides new insights into atmospheric VOCs. These findings are crucial for developing effective air pollution control strategies and improving air quality. This study emphasizes the importance of OVOCs, especially aldehydes and phenols, in the mechanism of summer O₃ generation. Full article

This study aimed to determine carbonyl compound concentrations and assess their potential health risk in indoor air at three homes in different areas of the Mexico City Metropolitan Area (MCMA) during the COVID-19 lockdown. Sampling was conducted from March to April 2021, during the home office confinement period. Average concentrations of formaldehyde, acetaldehyde, acrolein, acetone, propionaldehyde, and butyraldehyde in living rooms ranged from 84.15 to 74.93 μg m⁻³, 66.49 to 50.20 μg m⁻³, 60.01 to 41.35 μg m⁻³, 74.58 to 63.02 μg m⁻³, 10.90 to 6.21 μg m⁻³, and 12.45 to 9.91 μg m⁻³, respectively. In bedrooms, concentrations ranged from 84.76 to 59.70 μg m⁻³, 50.12 to 51.73 μg m⁻³, 59.74 to 37.25 μg m⁻³, 76.62 to 59.72 μg m⁻³, 14.45 to 8.40 μg m⁻³, and 10.72 to 8.82 μg m⁻³, respectively. All measured carbonyls had significant indoor concentrations, exceeding those reported in other studies worldwide. From the statistical analysis, it was found that there were significant differences in carbonyl levels between the studied homes. This suggests diverse and prevalent sources in these environments. E-cigarette vapors clearly increased acrolein levels, and the use of personal care and household products (PCHPs) also contributed to higher carbonyl concentrations indoors. The lifetime cancer risk coefficient (LTCR) and hazard quotient (HQ) values for formaldehyde and acetaldehyde exceeded WHO and US EPA recommendations, indicating increased risks of both carcinogenic and non-carcinogenic effects. Full article

In this study, the evolved gas analysis of polypropylene (PP), mixed wood biomass (WB), cardboard (CB), and their blends was investigated using a coupled thermo-gravimetric analysis–Fourier transform infrared spectroscopy (TG–FTIR) approach. The data obtained were used to semi-quantify the yield of volatile products from the individual feedstocks and their blends. Using N₂/O₂ (80/20) as the gasifying agent, the TG–FTIR setup was operated from ambient temperature to 850 °C at heating rates of 20 and 40 °C/min. The results indicated that the C–H stretching functional group exhibited higher yields in blends with greater PP mass percentages. In the CB/WB blends, C–H stretching recorded the lowest yield, ranging from 5 to 10 a.u. Conversely, blends containing an average PP mass of 16% showed C–H yields between 20 and 25 a.u. The levels of C–H were observed to increase proportionally with the PP mass fraction in the sample. Furthermore, the evolution of gases from carbonyl functional groups was the highest in the three-component blend with equal mass percentages, with C=O yields reaching 20–25 a.u. at 20 °C/min and 35–40 a.u. at 40 °C/min. The production of carbon monoxide (CO) was also highest in the three-component blend with equal mass percentages, yielding 9–10 a.u. Among the two-component blends, the PP/CB 50/50% blend exhibited the highest CO levels, ranging from 8 to 9 a.u. Overall, higher heating rates resulted in comparatively greater yields across all functional groups, particularly for C–H volatiles. These findings underscore the significance of blend composition and thermal ramping in optimising gasification performance. The results contribute to a deeper understanding of co-gasification dynamics and support the development of targeted feedstock strategies for efficient thermochemical conversion and improved control over volatile emissions. Full article

The growing dependence on fossil fuels has raised concerns over energy security, resource depletion, and environmental impacts, driving the need for renewable alternatives. Coffee husk, a widely available agro-industrial residue, represents an underutilized feedstock for biodiesel production. In this study, biodiesel was synthesized from coffee husk oil using a two-step transesterification process to address its high free fatty acid content (21%). Physicochemical analysis showed that Coffee Husk Oil Methyl Ester (CHOME) possessed a density of 863 kg m⁻³, viscosity of 4.85 cSt, and calorific value of 33.51 MJ kg⁻¹, compared to diesel with 812 kg m⁻³, 2.3 cSt, and 42.4 MJ kg⁻¹. FTIR analysis confirmed the presence of ester carbonyl and C–O functional groups characteristic of CHOME, influencing its combustion behavior. Engine tests were then conducted using B0, B10, B30, B50, and B100 blends under different loads, both with and without fuel preheating. Results showed that neat CHOME (B100) exhibited 11.8% lower brake thermal efficiency (BTE) than diesel, but preheating at 95 °C improved BTE by 5%, with preheated B10 slightly surpassing diesel by 0.5%. Preheating also reduced brake-specific fuel consumption by up to 7.75%. Emission analysis revealed that B100 achieved reductions of 6.4% CO, 8.3% HC, and 7.0% smoke opacity, while NOx increased only marginally (2.86%). Overall, fuel preheating effectively mitigated viscosity-related drawbacks, enabling coffee husk biodiesel to deliver competitive performance with lower emissions, highlighting its potential as a sustainable waste-to-energy fuel. Full article

Four 8-acyl-1-pyrrolidinylnaphalenes are prepared where the acyl group is pivaloyl (6), benzoyl (7), benzyloxycarbonyl (8), and ethyloxycarbonyl (9). Crystal structures for 6–8 show that both the carbonyl and pyrrolidinyl groups are nearly perpendicular to the naphthalene ring. Esters 8 and 9 fluoresce more strongly than ketones 6 and 7. All show some solvatofluoro-chromic emission from a charge-transfer excited state. Calculations suggest that both the acyl and amino groups twist back toward planarity with the naphthalene in the relaxed first singlet excited state. With 8 and 9, co-planarity is within 20°, while with 6 and 7, the carbonyl approaches no closer than 30°. With 6 and 7, the charge-transfer emission is replaced with a shorter wavelength band with more polar solvents. Despite the twisted geometries and steric interference toward planarization, these systems do not show emission from a twisted intramolecular charge-transfer (TICT) state. Full article

Four biomass residues–rosemary pomace, rosemary cake, grape seed and apple pomace–were torrefied at 250, 350 and 450 °C, and the physical, chemical and structural changes were characterized. The mass and energy yield decreased with increasing torrefaction temperature; the lowest mass (~10.4%) and energy yield (~10.6%) were observed for rosemary cake torrefied at 450 °C. The HHV increased the most for all feedstocks at 350 °C, with rosemary cake reaching a peak value of 36.4 MJ/kg at 350 °C. Ash content increased with temperature due to organic mass loss, while volatiles decreased and fixed carbon increased in most samples. The FTIR spectra showed the progressive loss of hydroxyl, carbonyl and C–O functionalities and the appearance of aromatic C=C bonds, indicating the formation of the biochar. TGA and DTG analyses revealed that the torrefied samples exhibited higher initial and maximum temperatures for decomposition, confirming improved thermal stability. The TGA-FTIR analyses of gas emissions during pyrolysis and combustion showed that the emissions of CO₂, CH₄, NO_x and SO₂ decreased with increasing degree of torrefaction. Overall, 350 °C was optimal to maximize energy density. The results show that agro-industrial residues can be effectively converted into sustainable biofuels, which offer the dual benefit of reducing waste disposal problems and providing a renewable alternative. In practice, such residues could be used for decentralized power generation in rural areas, co-combustion in existing power plants, or as feedstock for advanced bioenergy systems. Full article

Advances in OLED display technology have increased the demand for high-performance luminescent materials, yet efficient red emitters with narrow emission spectra remain rare. Here, two new polycyclic compounds (O-QA and S-QA) are designed by incorporating oxygen/sulfur into a carbonyl/nitrogen skeleton. Photophysical and theoretical studies reveal their hybridized local and charge-transfer state characteristics. In toluene, O-QA and S-QA show photoluminescence peaks at 586/579 nm with narrow emission spectra, while doped films exhibit strong red emissions peaking at 598/600 nm with high PL quantum yields of 67%/60%. The OLEDs using these emitters achieve red electroluminescence (EL) peaks at 598/602 nm, and attain maximum external quantum efficiencies of 7.36%/14.54%. This work may provide guidance for the development of narrow-spectrum red emitters based on carbonyl/nitrogen frameworks. Full article

We hypothesized that compounds containing ether linkages within their backbone structures, when exposed to hydroxyl radicals (•OH), can generate ultra-weak photon emission (UPE) as a result of the formation of triplet excited carbonyl species (³R=O*). To evaluate this hypothesis, we investigated the UPE of four compounds, each at a final concentration of 185.2 µmol/L: EGTA (ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid), a potent chelator of divalent cations, and three crown ethers—12-crown-4, 15-crown-5, and 18-crown-6—containing two, four, five, and six ether bonds, respectively. •OH was generated using a modified Fenton reagent—92.6 µmol/L Fe²⁺ and 2.6 mmol/L H₂O₂. The highest UPE was recorded for the Fe²⁺–EGTA–H₂O₂ (2863 ± 158 RLU; relative light units), followed by 18-crown-6, 15-crown-5, and 12-crown-4 (1161 ± 78, 615± 86, and 579 ± 109 RLU, respectively; p < 0.05), corresponding to the number of ether groups present. Controls lacking either H₂O₂ or Fe²⁺ exhibited no significant light emission compared to the buffer medium. These findings support the hypothesis that ether bonds, when oxidatively attacked by •OH, undergo chemical transformations resulting in the formation of ³R=O* species, the decay of which is associated with UPE. In crown ethers exposed to Fe²⁺-H₂O₂, the intensity of UPE was correlated with the number of ether bonds in their structure. Full article