Search Results (83)

Direct Air Capture (DAC) is gaining worldwide attention as a negative emissions strategy critical to meeting climate targets. Among emerging DAC materials, pyrolysis chars (PCs) and gasification chars (GCs) derived from biomass present a promising pathway due to their tunable porosity, surface chemistry, and low-cost feedstocks. This review critically examines the current state of research on the physicochemical properties of PCs and GCs relevant to CO₂ adsorption, including surface area, pore structure, surface functionality and aromaticity. Comparative analyses show that chemical activation, especially with KOH, can significantly improve CO₂ adsorption capacity, with some PCs achieving more than 308 mg/g (100 kPa CO₂, 25 °C). Additionally, nitrogen and sulfur doping further improves the affinity for CO₂ through increased surface basicity. GCs, although inherently more porous, often require additional modification to achieve a similar adsorption capacity. Importantly, the long-term stability and regeneration potential of these chars remain underexplored, but are essential for practical DAC applications and economic viability. The paper identifies critical research gaps related to material design and techno-economic feasibility. Future directions emphasize the need for integrated multiscale research that bridges material science, process optimization, and real-world DAC deployment. A synthesis of findings and a research outlook are provided to support the advancement of carbon-negative technologies using thermochemically derived biomass chars. Full article

Weathering steel (WS) is widely used in bridge construction due to its high corrosion resistance, durability, and low maintenance requirements. This paper reviews the performance of WS bridges in Canadian climates, focusing on the formation of protective patina, influencing factors, and long-term maintenance strategies. The protective patina, composed of stable iron oxyhydroxides, develops over time under favorable wet–dry cycles but can be disrupted by environmental aggressors such as chlorides, sulfur dioxide, and prolonged moisture exposure. Key alloying elements like Cu, Cr, Ni, and Nb enhance corrosion resistance, while design considerations—such as drainage optimization and avoidance of crevices—are critical for performance. The study highlights the vulnerability of WS bridges to microenvironments, including de-icing salt exposure, coastal humidity, and debris accumulation. Regular inspections and maintenance, such as debris removal, drainage system upkeep, and targeted cleaning, are essential to mitigate corrosion risks. Climate change exacerbates challenges, with rising temperatures, altered precipitation patterns, and ocean acidification accelerating corrosion in coastal regions. Future research directions include optimizing WS compositions with advanced alloys (e.g., rare earth elements) and integrating climate-resilient design practices. This review highlights the need for a holistic approach combining material science, proactive maintenance, and adaptive design to ensure the longevity of WS bridges in evolving environmental conditions. Full article

Epoxy resins are widely used as protective coatings in civil infrastructure, yet sulfate-rich environments accelerate their deterioration. This study evaluates the effectiveness of multi-walled carbon nanotubes (MWCNTs) in enhancing the sulfate resistance of epoxy resins. Neat and MWCNT-reinforced epoxy specimens (0.25 wt.% and 0.5 wt.%) were fabricated, heat cured at 100 °C and exposed to a solution of sulfuric acid and sodium chloride maintaining a pH of less than 3 for 0, 30, and 60 days. Analytical techniques, including scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), revealed distinct degradation patterns: the neat epoxy exhibited puncture damage and extensive salt deposition, while the MWCNT-reinforced specimens showed crack propagation mitigated by nanotube bridging. Heat curing introduced micro-voids that exacerbated sulfate ingress. The salt deposition surged to 200 times for the MWCNT-reinforced specimens compared to the neat ones, whereas crack width was higher in the MWCNT reinforced specimen compared to their neat counterparts, given that crack-bridging was observed. These findings highlight the potential of MWCNTs to improve epoxy durability in sulfate-prone environments, though the optimization of curing conditions and dispersion methods is critical. Full article

The eight new copper(II), nickel(II), zinc(II), and iron(III) coordination compounds [Cu(L)Cl]₂ (1), [Cu(L)Br]₂ (2), [Cu(L)(NO₃)]₂ (3), [Cu(phen)(L)]NO₃ (4), [Ni(HL)₂](NO₃)₂·H₂O (5), [Ni(HL)₂]Cl₂ (6), [Zn(L)₂]·0.125H₂O (7), and [Fe(L)₂]Cl (8), where HL stands for 2-benzoylpyridine 4-allylthiosemicarbazone, were synthesized and characterized. ¹H, ¹³C NMR, and FTIR spectroscopies were used for characterization of the HL thiosemicarbazone. The elemental analysis, the FTIR spectroscopy, and the study of molar electrical conductivity were used for characterization of the coordination compounds 1–8. Also, the crystal structures of HL, its salts ([H₂L]Cl; [H₂L]NO₃), and complexes 1, 3, 5, 7, and 8 were determined using single-crystal X-ray diffraction analysis. Complexes 5, 7, 8 have mononuclear structures, while copper(II) complexes 1 and 3 have a dimeric structure with the sulfur atoms of the thiosemicarbazone ligand bridging two copper atoms together. Thiosemicarbazone HL and the complexes manifest antibacterial and antifungal activities. The studied substances are more active towards Gram-negative bacteria than towards Gram-positive bacteria and fungi. Complex 1 is the most active one towards Gram-positive bacteria and C. albicans, while the introduction of 1,10-phenanthroline into the inner sphere enhances the activity towards Gram-negative bacteria. Thiosemicarbazone and complexes 6 and 7 manifest antiradical activity that exceeds the activity of Trolox. HL and complex 1 manifest antiproliferative activity towards HL-60 cancer cells which exceeds the activity of their analogs with 2-formyl-/2-acetylpyridine 4-allylthiosemicarbazone. Full article

Albumin-based nanoparticles are promising drug delivery systems due to their biocompatibility, biodegradability, and ability to improve targeted drug release. Among various preparation methods, radiation-induced cross-linking in the presence of ethanol has been proposed in the literature as an effective method for producing protein nanoparticles with preserved bioactivity and controlled size. However, the mechanisms by which ethanol radicals contribute to protein aggregation remain insufficiently understood. In this study, we investigate the role of ethanol in the aggregation of albumins to determine whether its presence is necessary or beneficial for nanoparticle formation. Using pulse radiolysis, spectroscopy methods, resonance light scattering (RLS), and near-infrared (NIR) spectroscopy, we examined aqueous ethanol solutions of albumins before and after irradiation. Our results show that ethanol concentrations above 40% (v/v) significantly promote both radiation-induced and spontaneous protein aggregation. Mechanistic analysis indicates that ethanol radicals react with albumin similarly to hydrated electrons, mainly targeting disulfide bridges. This reaction leads to the formation of sulfur-centered radicals and the formation of intermolecular disulfide bonds that stabilize protein nanostructures by excluding the formation of dityrosine bridges, as described in the literature. In contrast, ethanol concentration below 40% does not favor the radiation-induced aggregation compared to the solution containing t-BuOH. These results provide novel insights into the role of organic cosolvents in protein aggregation and contribute to a broader understanding of the mechanisms of formation of albumin-based nanoparticles using ionizing radiation. Full article

DNA phosphorothioate (PT) modifications, characterized by the replacement of a non-bridging phosphate oxygen atom with a sulfur atom, are widely observed in bacterial genomes. Sensitive detection of phosphorothioate is crucial for elucidating their biological roles and functions. Herein, we developed an innovative method that leverages oligonucleotide-templated reactions (OTRs) and fluorogenic oligonucleotide probes. By optimizing temperature, probe sequence length, and the relative distance between PT position and the fluorophore probe, we achieved sensitive detection for DNA PT modifications through fluorogenic signal amplification, which provides an efficient and cost-effective approach for sensitive detection of phosphorothioate-modified DNA. Full article

Biochar, an eco-friendly soil amendment, holds promise for remediating contaminated soils, yet its impacts on coastal wetland soils under combined microplastic (MP) and heavy metal (HM) pollution remain underexplored. This study examined the efficacy of 2% Spartina alterniflora-derived biochar (BC) in rehabilitating soils co-contaminated with cadmium (Cd) and two MPs—polyethylene (PE) and polylactic acid (PLA)—at 0.2% and 2% (w/w). The results indicated that biochar significantly elevated soil pH (8.35–8.43) and restored electrical conductivity (EC) to near-control levels, while enhancing organic matter content (up to 130% in PLA-contaminated soils), nutrient availability (e.g., phosphorus, potassium), and enzyme activity. Biochar reduced bioavailable Cd by 14–15% through adsorption and ion exchange. Although bacterial richness and diversity slightly declined, biochar reshaped microbial communities, enriching taxa linked to pollutant degradation (e.g., Proteobacteria, Bacteroidota) and upregulated functional genes associated with carbon, nitrogen, and sulfur cycling. Additionally, biochar boosted Suaeda salsa (S. salsa) biomass (e.g., 0.72 g/plant in A1B) and height (e.g., 14.07 cm in E1B) while reducing Cd accumulation (29.45% in shoots) and translocation. Remediation efficiency was most pronounced in soils with 0.2% PLA. These findings bridge critical knowledge gaps in biochar’s role in complexly polluted coastal wetlands and validate its potential for sustainable soil restoration. Full article

Homopolyatomic cations of the main group elements and of the element sulfur, in particular, are used as tutorial examples to teach structure and bonding in inorganic chemistry. So far, the cations [S₄]²⁺, [S₈]²⁺, [S₁₉]²⁺, [S₅]^•+, and [S₈]^•+ are known experimentally. In this report, the generation and crystal structure determination of the salt Na₂[S₂₀]₂[B₁₂Cl₁₂]₃, containing the new homopolyatomic sulfur cation [S₂₀]²⁺, is reported. The structure of the latter cation consists of two seven-membered homocycles, which are bridged by a six-membered sulfur chain. This structure is strongly related to that of [S₁₉]²⁺. The heptasulfur rings show pronounced bond alternation. Comparison with the experimental structures of [S₇X]⁺ (X = I, Br) and the application of quantum chemical calculations show unambiguously that the observed structural features are intrinsic properties of the cationic cyclo-heptasulfur moieties. The latter can occupy different conformations, which only slightly differ in energy. Charge delocalization and negative hyperconjugation contribute to the stability of the observed structures. The discovery of the [S₂₀]²⁺ cation fits well into range of known homopolyatomic sulfur cations, which can be classified by their averaged oxidation state of sulfur. Full article

Addressing the complex physicochemical properties of coal gangue from typical mining areas in Inner Mongolia, this study focuses on this area’s abundant reserves coupled with the low utilization rate and significant strength variability of ecological slope protection materials. Notably, research on the alkalization–carbonization of coal gangue remains scarce. To bridge this gap, we propose a method leveraging the moisture migration behavior of coal gangue porous media. By utilizing continuous displacement high-temperature steam carbon sequestration enhancement technology, internal moisture is gradually and precisely controlled to induce the formation of high-temperature carbonic acid gas. This process facilitates internal carbon sequestration and effectively locks in the sequestration effect. This approach enables effective loading of sulfurized CO₂ composite gases in a reversible manner, achieving passive carbon sequestration driven by moisture migration. Consequently, it enhances the negative carbon content within the aggregates while bolstering their mechanical properties. After alkalization pretreatment with various concentrations and three hours of carbon sequestration, the microhardness of the aggregate surface and transition zone were observed to have increased by 24.3% and 36.4%, respectively. Additionally, the compressive and splitting tensile strengths of coal gangue concrete rose by 4.8 MPa and 0.4 MPa, respectively, while porosity decreased by up to 3.6%, and the proportion of harmful pores dropped from 11.22% to 6.54%. A strong correlation between the proportion of harmless/low-harm pores and strength development was observed. Overall, the high-temperature carbonic acid steam displacement method with sulfurized CO₂ composite gases effectively improves the physicochemical properties of coal gangue aggregates and enhances surface activity and hydration in the interface transition zone, meeting the engineering standards for in situ ecological remediation in Inner Mongolia’s mining areas. Full article

Cement Asphalt Mortar (CAM) is widely applied in infrastructure, particularly in railways, bridge expansion joints, and pavements, due to its combination of cement’s load-bearing capacity and asphalt’s flexibility. Conventional CAM formulations, however, often encounter challenges such as extended setting times, high shrinkage, and limited durability under extreme environmental conditions. This study addresses these limitations by integrating bio-oil and polymer additives to enhance both the sustainability and performance of CAM mixtures. CAM mixtures were evaluated with cement-to-asphalt emulsion (C/AE) mass ratios of 75:25 and 50:50, incorporating bio-oil contents of 2% and 4% by mass and latex–acrylic polymer proportions ranging from 1% to 2% by mass. The optimized mix design, with a 75:25 cement-to-asphalt emulsion (C/AE) mass ratio, 2% bio-oil, and 1.5% polymer, improved flowability by 25%. This formulation achieved a flow diameter of approximately 205 mm and reduced the flow time to 72 s. Compressive strength tests indicated that this formulation reached an early-stage strength of 10.45 MPa (a 20.8% improvement over the control) and a 28-day strength of 24.18 MPa. Thermal stability tests at 45 °C demonstrated that the optimized CAM retained 86.6% of its compressive strength, compared to a 25% reduction in unmodified mixtures. Chemical resistance assessments in 5% sulfuric acid and 5% sodium hydroxide solutions showed strength retention of 95.03% and 91.98%, respectively, outperforming control mixtures by 17% and 13%. SEM examination revealed a dense, cohesive microstructure, reducing shrinkage to 0.01% from 0.15% in the control. These findings underscore the potential of bio-oil and latex–acrylic polymers to improve the performance and sustainability of CAM mixtures, making them well suited for resilient, rapid-setting infrastructure applications. Full article

2,6-Dipicolinoylbis(N,N-dialkylthioureas), H₂L^R, readily react with uranyl salts under formation of monomeric or dimeric complexes of the compositions [UO₂(L^R)(solv)] (solv = donor solvents such as H₂O, MeOH or DMF) or [{UO₂(L^R)(µ-OMe)}₂]²⁻ (1). In such complexes, the uranyl ions are exclusively coordinated by the “hard” O,N,O or N,N,N donor atom sets of the central ligand unit and the lateral sulfur donor atoms do not participate in the coordination. Different conformations have been found for the dimeric anions. The bridging methanolato ligands and the four uncoordinated sulfur atoms can adopt different orientations with respect to the equatorial coordination spheres of the uranyl units. The presence of non-coordinated sulfur atoms offers the opportunity for the coordination of additional, preferably “soft” metal ions. Thus, reactions with [AuCl(PPh₃)], lead acetate or acetates of transition metal ions such as Ni²⁺, Co²⁺, Fe²⁺, Mn²⁺, Zn²⁺, or Cd²⁺, were considered for the syntheses of bimetallic complexes. Various oligometallic complexes with uranyl units were prepared: [{UO₂(L^R)(μ-OMe)(Au(PPh₃)}₂] (2), [(UO₂)₃Pb₂(L^R)₄(MeOH)₂(μ-OMe)₂] (3), [M{UO₂(L^R)(OAc)}₂] (M= Zn, Ni, Co, Fe, Mn or Cd) (R = Et: 5, RR = morph: 6), or [(UO₂)(NiI)₂(L^R)₂] (7). The products were extensively studied spectroscopically and by X-ray diffraction. Full article

This study explores the enhanced removal of refractory organic compounds from coking wastewater using polyaluminum chloride (PACl) with two different basicity levels (0.5 and 2.5), in combination with coagulant aids such as cationic polyacrylamide (CPAM) and iron ions. The results demonstrated that both PACl formulations significantly outperformed commercial PACl in terms of COD and color removal, with PACl at the basicity of 2.5 achieving slightly higher efficiency than PACl at the basicity of 0.5. The improved performance was attributed to the higher content of polymeric aluminum species, enhancing charge neutralization and bridging adsorption. The addition of coagulant aids further improved the performance, with PACl at the basicity of 2.5 combined with iron ions achieving the highest COD (48.41%) and color removal (80.77%), due to sweep coagulation and complexation. Organic composition analysis using gas chromatography–mass spectrometry (GC-MS), three-dimensional excitation–emission matrix (3D-EEM) fluorescence spectroscopy, and ultraviolet (UV) spectroscopy indicated that PACl combined with iron ions was the most effective in removing polycyclic aromatic hydrocarbons (PAHs) and nitrogen-, oxygen-, and sulfur-containing heterocyclic compounds. Additionally, a floc analysis showed that the flocs formed with iron ions were more compact and had better settleability compared to those formed with CPAM, further contributing to the improved coagulation efficiency. These results highlight the importance of optimizing the PACl basicity and coagulant aid selection for the enhanced removal of refractory organic compounds from coking wastewater, offering a promising strategy for advanced wastewater treatment. Full article

Cys is one of the least abundant amino acids in proteins. However, it is often highly conserved and is usually found in important structural and functional regions of proteins. Its unique chemical properties allow it to undergo several post-translational modifications, many of which are mediated by reactive oxygen, nitrogen, sulfur, or carbonyl species. Thus, in addition to their role in catalysis, protein stability, and metal binding, Cys residues are crucial for the redox regulation of metabolism and signal transduction. In this review, we discuss Cys post-translational modifications (PTMs) and their role in plant metabolism and signal transduction. These modifications include the oxidation of the thiol group (S-sulfenylation, S-sulfinylation and S-sulfonylation), the formation of disulfide bridges, S-glutathionylation, persulfidation, S-cyanylation S-nitrosation, S-carbonylation, S-acylation, prenylation, CoAlation, and the formation of thiohemiacetal. For each of these PTMs, we discuss the origin of the modifier, the mechanisms involved in PTM, and their reversibility. Examples of the involvement of Cys PTMs in the modulation of protein structure, function, stability, and localization are presented to highlight their importance in the regulation of plant metabolic and signaling pathways. Full article

The reactions of radicals with human serum albumin (HSA) under reductive stress conditions were studied using pulse radiolysis and photochemical methods. It was proved that irradiation of HSA solutions under reductive stress conditions results in the formation of stable protein aggregates. HSA aggregates induced by ionizing radiation are characterized by unique emission, different from the UV emission of non-irradiated solutions. The comparison of transient absorption spectra and the reactivity of hydrated electrons ($e_{aq}^{-}$) with amino acids or HSA suggests that electron attachment to disulfide bonds is responsible for the transient spectrum recorded in the case of albumin solutions. The reactions of $e_{aq}^{-}$ and ${CO}_2^{•-}$ with HSA lead to the formation of the same products. Recombination of sulfur-centered radicals plays a crucial role in the generation of HSA nanoparticles, which are stabilized by intermolecular disulfide bonds. The process of creating disulfide bridges under the influence of ionizing radiation is a promising method for the synthesis of biocompatible protein nanostructures for medical applications. Our Raman spectroscopy studies indicate strong modification of disulfide bonds and confirm the aggregation of albumins as well. Low-temperature measurements indicate the possibility of electron tunneling through the HSA protein structure to specific CyS-SCy bridges. The current study showed that the efficiency of HSA aggregation depends on two main factors: dose rate (number of pulses per unit time in the case of pulse radiolysis) and the temperature of the irradiated solution. Full article

The inadequate disposal of tires poses a significant threat to human health and requires effective recycling solutions. The crosslinked structure of rubber, formed through sulfur bridges during vulcanization, presents a major challenge for recycling because it prevents the rubber scraps from being reshaped thermoplastically. Reclaiming or devulcanization aims to reverse this crosslinking, allowing waste rubber to be transformed into products that can be reprocessed and revulcanized, thereby saving costs and preserving resources. Microwave technology shows promise for devulcanization due to its ability to break sulfur crosslinks. In this study, we investigate the devulcanization of ground tire rubber (GTR) through a combined process applied to samples from both car and truck tires subjected to varying periods of microwave irradiation (0, 3, 5 and 10 min). The devulcanized GTR was then blended with natural rubber (NR) and underwent a new vulcanization process, simulating recycling for novel applications. The GTR was mixed with NR in proportions of 0, 10, 30 and 50 parts per hundred rubber (phr). This study also examines the differences between the GTR from car tires and GTR from truck tires. The results showed that the treatment effectively breaks the crosslinks in the GTR, creating double bonds (C=C) and improving the mechanical properties of the revulcanized samples. The crosslinking density and related properties of the samples increased with treatment time, reaching a maximum at 5 min of microwave treatment, followed by a decrease at 10 min. Additionally, the incorporation of GTR enhanced the thermal stability of the resulting materials. Full article