Search Results (251)

In this study, nine barium sulfate (BaSO₄)-supported heterogeneous catalysts (C1–C9) were synthesized via three modification strategies: stearic acid coating (C1–C3), physical doping (C4, C6, and C8), and sol-gel processing with calcination (C5, C7, and C9). Their comprehensive characterization revealed that sol-gel-synthesized C7 exhibited the most favorable surface properties, including well-dispersed Al–O–Si species, tetrahedrally coordinated Al³⁺, and abundant Brønsted acid sites. Their catalytic performance was evaluated in the chlorination of toluene, fluorobenzene, bromobenzene, and iodobenzene, using hydrochloric acid (HCl) as the chlorine source and either hydrogen peroxide (H₂O₂) or ammonium persulfate ((NH₄)₂S₂O₈) as the oxidant. C7 achieved complete toluene conversion (100%) at 60 °C under optimized conditions and exhibited high conversions of fluorobenzene (55%), bromobenzene (76%), and iodobenzene (46%). Notably, ammonium persulfate enabled a unique in situ halogen exchange pathway, yielding chlorobenzene as the exclusive product from bromobenzene and iodobenzene. XRD and XPS analysis of crystalline by-products confirmed the formation of NH₄HSO₄, BaSO₄, and NH₄Cl, providing evidence for the persulfate-driven radical mechanism. Iodine detection in upper-layer crystals confirmed iodobenzene products, while the absence of chlorine signals in the upper layer confirmed separation of organic and inorganic species. The detection of barium sulfate peaks confirms that the catalyst support retains its structural integrity under harsh reaction conditions, demonstrating chemical stability and reusability potential. Collectively, these findings establish a clear structure–activity relationship and demonstrate that the synergy between modified BaSO₄ surfaces and persulfate-generated radicals provides an efficient, sustainable platform for aromatic chlorination, offering significant potential for pharmaceutical, agrochemical, and fine chemical manufacturing applications. Full article

A series of gallium and indium complexes bearing pyridine-2,6-bis(phenolate) ligands with ortho-substituents of increasing steric bulk (^tBu, SiMe₃, SiPh₃) was synthesized via SiMe₄ elimination from M(CH₂SiMe₃)₃ (M = Ga, In). The gallium complexes 2a–c were structurally characterized by X-ray diffraction, revealing monomeric four-coordinate distorted trigonal pyramidal geometries. DOSY NMR studies revealed that the indium complexes 3a (^tBu) and 3b (SiMe₃) are dimeric in solution, whereas the bulkier 3c (SiPh₃) is monomeric. All complexes were tested as initiators for ring-opening polymerization (ROP) of ε-caprolactone, L-lactide, and rac-lactide in the presence of benzyl alcohol. The M-CH₂SiMe₃ bond is inert toward alcohols, pointing to an activated monomer mechanism. Indium complexes exhibited higher activity than their gallium analogues, and the activity strongly depends on the ligand steric bulk: the most hindered SiPh₃ derivative 3c showed the highest activity, reaching full ε-CL conversion in 24 h at 80 °C, whereas the analogous gallium complex 2c was almost inactive. Full article

Groundwater is the principal source of drinking water in northern Ghana, where fluoride and nitrate are the major groundwater-quality concerns. Naturally elevated fluoride concentrations (>1.5 mg/L) have resulted in the closure of wells, while nitrate pollution regularly occurs in shallow aquifers due to lack of sanitation infrastructure and agricultural activities. Distinguishing natural from human-induced groundwater contamination is therefore essential for effective groundwater management. This study assessed groundwater quality with regard to fluoride enrichment and established lithology-specific natural background levels (NBLs) for major ions and selected trace elements using groundwater samples from 110 wells across three different lithologies in the Vea Catchment, northern Ghana. The results reveal high fluoride NBLs in a K-feldspar-rich granitoid formation (3.84 mg/L) and near-guideline concentrations in a hornblende–biotite tonalite (1.41 mg/L). Silicate weathering, lithology-dependent dissolution of fluorine-bearing minerals, and cation exchange were identified as the principal processes controlling groundwater chemistry and fluoride enrichment. Elevated NBLs of Sr, Li, Ba and SiO₂ in the K-feldspar-rich granitoids indicate enhanced water–rock interaction whereas relationships between nitrate and Cl⁻, Br⁻, and SO₄²⁻ suggest localized anthropogenic impacts. These findings demonstrate the value of lithology-specific NBLs for improving groundwater quality assessment and supporting groundwater resource management in crystalline basement aquifers. Full article

This study assessed the effects of groundwater interacting with aggregate produced from steel slag, used as a ballast material in a waterproofing system protecting the road surface under high groundwater table conditions. Field investigations were carried out, with hydrochemical analyses of groundwater and water draining through the structure, mineralogical characterisation of the slag, and geochemical modelling using the PHREEQC programme with inverse modelling. The results showed that water flow through the slag aggregate caused strong alkalisation of the solution and changes in the concentrations of Ca, Mg, Na, Cl, sulphates and carbonate components. Inverse modelling enabled the identification of eight acceptable mass balance models. The main primary phases involved in the transformations were larnite, merwinite, mayenite, halite and, locally, slag glass. Their dissolution contributed Ca, Mg, Al, Si, Na and Cl to the solution. The increases in Na and Cl concentrations were interpreted primarily as the result of an external influx of road salt, rather than as an intrinsic property of the slag. The secondary products were dominated by amorphous silica, calcite, ettringite and brucite, indicating silica removal, carbonation, sulphate fixation and the partial immobilisation of Mg. The results confirm that slag aggregate remains geochemically active in contact with groundwater; however, simultaneous carbonation and secondary mineralisation favour the gradual stabilisation of the water–slag system. Full article

Improving the separation efficiency between methyldichlorosilane (CH₃SiHCl₂) and trichlorosilane (SiHCl₃) is one of the key urgent problems to be solved for the quality improvement and consumption reduction in high-purity polysilicon. In this work, three types of porous supported catalysts were prepared via an in situ reaction method, taking aluminum chloride (AlCl₃) as the active component and activated carbon, silica gel and activated alumina as support; the catalytic reaction mechanisms of CH₃SiHCl₂ and silicon tetrachloride (SiCl₄) over the as-prepared porous supported catalysts were investigated, based on density functional theory (DFT). The results reveal that among the three supported catalysts, the activated carbon-supported aluminum chloride catalyst (C@AlCl₃) possesses the maximum binding energy (−3.20 eV) between the active component and support. CH₃SiHCl₂ and SiCl₄ possess the lowest co-adsorption energy (−1.8 eV) and the minimum reaction energy barrier (0.8 eV) on C@AlCl₃, accompanied by the maximum charge transfer to the catalyst surface (−2.65 e and −2.80 e), thus exhibiting the highest catalytic activity, with the maximum single-pass conversion of CH₃SiHCl₂ exceeding 90%. This work provides material basis and theoretical guidance for constructing a reactive distillation strategy for high-efficiency and low-energy separation of CH₃SiHCl₂ from SiHCl₃. Full article

This paper investigates the stress corrosion cracking (SCC) behavior under constant loading conditions and the early-stage grain-scale deformation mechanisms of a friction-stir-welded (FSW) joint of 7A52 aluminum alloy. The results show that when a constant load equivalent to 1.0 times the yield strength (439.43 MPa) of the base metal is applied, the joint fractures after 72 days of immersion in a 3.5 wt% NaCl solution, with the fracture located in the heat-affected zone on the advancing side (AS-HAZ). The fracture surface exhibits a mixed-mode morphology characterized by both brittle and ductile features. Observations suggest that cracks mainly initiate at the bottom of corrosion pits, at grain boundaries, and at the interfaces between precipitates (such as Mg-Si-rich, Al-Fe-rich, or Al-(FeMn)-rich) and the Al matrix. It is suggested that the initiation mechanisms are closely related to galvanic corrosion, interfacial weakening, and mechanical property mismatch. In situ tensile and EBSD results indicate that the AS-HAZ is the first region to undergo deformation. As the load increases from 400 N to 1500 N, the degree of strain localization intensifies, with high-strain regions preferentially concentrated at grain boundaries. Grain boundary damage is likely a key mechanism responsible for the initial failure on the advancing side of the FSW joint. Further in situ SEM observations reveal that during the early stage of tensile deformation, as the load increases from 300 N to 455 N, the grain surface in the AS-HAZ evolves from a flat morphology to a typical orange peel appearance. Meanwhile, grain boundaries change from clearly visible to blurred, slip traces increase, and multiple slip systems are activated within the grains. The continuous pile-up of dislocations at grain boundaries leads to a sharp increase in local stress concentration, ultimately inducing grain boundary instability and crack nucleation. Full article

This study investigates the influence of Lewis acids on a novel stratified (Co²⁺,Pd²⁺)₂SiO₄-Pd⁰ olivine catalyst for the Heck–Mizoroki coupling of iodobenzene and methyl acrylate. Comprehensive characterization (ICP-OES, Raman, P-XRD, XPS) confirms the successful synthesis of a material with surface-incorporated Pd²⁺ and bulk Pd⁰ nanoparticles within a Co₂SiO₄ matrix. The promoter-free system with triethylamine base achieved the highest initial rate of 3.92 × 10⁻⁷ mol.s⁻¹ with an average rate of 1.18 × 10⁻⁷ mol.s⁻¹, despite a 30 min induction period. However, ZnCl₂, the weakest acid, showed the most substrate activation and lowered the induction period to 10 min, while AlCl₃ also reduced the induction period to 20 min. FeCl₃ showed the poorest performance, attributed to redox-mediated site poisoning rather than hydrolysis. Selectivity over the catalyst was maintained at >99 mol% towards methyl cinnamate irrespective of the Lewis acid or base used. However, recycling of the catalyst led to a gradual decrease in selectivity toward methyl cinnamate from >99 mol% to ~94.6 mol% over three cycles, while conversion remained consistently high at >99 mol% across all cycles, indicating that the catalyst’s primary activity was largely preserved despite surface evolution toward side-product formation. Lewis acids were found to function primarily as surface modifiers and/or productive substrate activators, with stronger Lewis acids also targeting the olivine framework, as seen from the preferential leaching of Co relative to Pd. Full article

Sustaining human presence on the Moon depends on access to strategic metals, which can be achieved by directly utilizing extraterrestrial resources through in situ resource utilization (ISRU). This study presents novel insights and preliminary results into a previously unexplored strategy for metals extraction from the lunar regolith simulant Lunar Mare Soil (LMS-1) using deep eutectic solvents (DESs). Based on inductively coupled plasma–optical emission spectrometry (ICP-OES) measurements, the solubility of major oxide components of the regolith, SiO₂, Al₂O₃, TiO₂, Cr₂O₃, MgO and FeO_T, was investigated in ethaline (choline chloride:ethylene glycol, ChCl:EG) as well as reline (ChCl:Urea). Although both DESs enabled oxide dissolution, reline exhibited significantly higher dissolution efficiency, due to the additional hydrogen-bond donor sites, NH and CO groups from urea, as well as high chloride activity in the reline. Cyclic voltammetry (CV) and square wave voltammetry (SWV) revealed that dissolved metal species in the reline–regolith system undergo complex multivalent redox transitions. The equilibrium potentials of the metals were determined and correlated with the order in which the metals should be electrodeposited on the cathode from an electrolyte containing dissolved lunar regolith. Based on the data from electrochemical measurements, parameters for electrolysis were selected. At less negative overpotentials, the deposit consisted mainly of Si, while Al, Cr, and Fe, along with Si, were electrodeposited at more negative potentials. The results highlight the importance of considering the selective electrochemical extraction of metals from DESs using lunar regolith as the source. Full article

Proteases are among the most commercially important industrial enzymes, yet their large-scale production is often limited by complex and costly downstream processing. In this study, an integrated bioprocess was developed for the production, in situ recovery, and purification of an extracellular protease produced by Aspergillus sp. (SIS 22/UCP 1287) under submerged fermentation. Enzyme extraction was coupled directly to fermentation using a polyethylene glycol (PEG)–phosphate aqueous two-phase system (ATPS), aiming to enhance recovery while preserving enzymatic activity. The effects of PEG molecular weight, polymer and phosphate concentrations, and pH on enzyme partitioning were systematically investigated through a full factorial experimental design. Low-molecular-weight PEG and near-neutral pH conditions significantly favored enzyme migration to the PEG-rich phase. Under optimized conditions (15% PEG 3500, 20% phosphate, pH 7.0), the ATPS achieved a partition coefficient of 65.55, enzyme recovery of 209%, and a purification factor of 1.64. Subsequent purification by DEAE–Sephadex ion-exchange chromatography yielded a tenfold increase in specific activity, with optimal elution at 0.5 M NaCl. SDS–PAGE analysis confirmed the homogeneity of the purified protease, revealing a single band at approximately 59 kDa. Overall, the proposed integrated ATPS–chromatography strategy represents a robust, scalable, and environmentally friendly platform that significantly simplifies downstream processing while maintaining high enzyme activity, highlighting its potential for industrial and biotechnological applications. Full article

Soil salinization critically restricts melon production, and the seed germination stage is particularly vulnerable to saline–alkali stress (SAS). Although silicon (Si) is known to enhance plant stress tolerance, its role in alleviating SAS-induced inhibition of melon seed germination—particularly under combined neutral and alkaline salt stress—remains insufficiently characterized. Here, using the melon cultivar ‘Xinyinhui’, we simulated SAS with a mixture of NaCl and NaHCO₃ and screened for the optimal Si concentration. We then systematically examined physiological, biochemical, and gene expression responses. SAS significantly inhibited germination (20.4% reduction in germination rate; 56.9% in vigor index) and induced oxidative damage (MDA increased by 9.7%; superoxide anion by 170.6%), suppressed antioxidant enzyme activities (SOD −28.8%, POD −69.4%), and disturbed starch metabolism. Exogenous Si at 1.25 mmol·L⁻¹ effectively alleviated these effects: The germination rate increased from 71.7% to 88.8%, and SOD and POD activities increased by 26.7% and 63.6%, while MDA and superoxide anion decreased by 7.1% and 16.4%. Si also promoted starch degradation, as indicated by a 13.9% reduction in starch content, 8.4% increase in total amylase activity, and 23.2% upregulation of CmBMY expression. In addition, Si significantly improved root morphology: Root surface area, volume, branch number, and tip number increased by 19.8–326.3%, while the average root diameter decreased by 24.4%. These results suggest that exogenous Si alleviates SAS inhibition of melon seed germination through coordinated regulation of antioxidant defense and starch metabolism rather than through a single pathway. Our findings provide a physiological basis for the potential application of Si fertilizer in melon cultivation under saline–alkali conditions. Full article

Patterned lead-halide perovskite microstructures are promising for integrated optoelectronics, photonics, and polarization-sensitive devices, but the practical growth behavior of compositionally tunable microcrystals under simple static confinement remains insufficiently understood. Here, we investigate template-assisted confined crystallization of MAPbBr₃ and MAPbBr_3−xCl_x microstructures using patterned polydimethylsiloxane (PDMS) stamps. MAPbBr₃ was first examined as a reference system to evaluate pattern transfer, morphology, substrate compatibility, and characteristic growth imperfections. Periodic microstructures with template spacings from 0.8 to 10 μm were obtained on Si/SiO₂, ITO, PDMS, and MAPbBr₃ macrocrystal substrates. Static stamping creates strong edge–center morphological divergence: thick patterned microcrystals and coalesced domains formed preferentially near the sample edges, whereas thinner isolated microcrystal arrays were more common in central regions. XRD, AFM, SEM, SAED, EDX, HRTEM, PL microscopy, and TRPL analyses show that the method can generate well-crystallized and optically active perovskite domains while also producing multidomain aggregates, incomplete pattern transfer, pressure-induced wrinkling, and nanoscale secondary crystallites. Extension to MAPbBr_3−xCl_x demonstrates that patterned mixed-halide microstructures can be obtained with composition-dependent structural and optical properties. Nevertheless, XRD, EDX, PL, and TRPL results indicate that Cl-rich samples are not fully described by a simple homogeneous solid-solution model, likely involving compositionally heterogeneous crystallization and a Br-rich emissive component. Preliminary MAPbCl₃-on-MAPbBr₃ experiments further show that PDMS-confined patterning can be coupled with substrate-mediated halide exchange or interfacial recrystallization. Overall, static PDMS-confined crystallization is established as a simple exploratory platform for producing diverse patterned perovskite microstructures. This approach is well-suited for the manual selection of suitable crystals and the fabrication of individual microdevices; however, improved control over pressure, mass transport, nucleation localization, and composition will be required when the uniformity of produced patterned microcrystals is desired. Full article

The article presents the synthesis and characterization of double halide perovskites (DHPs) with the nominal composition Cs₂Ag_0.2Na_0.4In_0.6M_0.4Cl₆ (M = Si, Ti, Zr), including photoluminescence (PL), photoluminescence excitation (PLE) spectra measured over a range of temperatures and kinetics of luminescence. The materials were synthesized via a hydrothermal method. The phase purity and elemental composition of the synthesized perovskites were confirmed by X-ray diffraction (XRD), Rietveld refinement, scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS) and elemental analysis, which demonstrated that the samples showed a close match to the target stoichiometry. The PL spectra exhibit a systematic shift toward the lower-energy region with substitution from Si to Zr, correlating with the progressive increase in the ionic radii of the substituting cations. All samples display broad, asymmetric emission bands, characteristic of self-trapped excitonic (STE) states. Temperature-dependent PL measurements reveal a gradual decrease in emission intensity with increasing temperature for all samples. The maximum emission intensity is observed in the range of ~160–200 K, corresponding to optimal conditions for radiative recombination, whereas the lowest intensity is recorded at ~80–100 K, where thermal activation of radiative centers is minimal. An increase in temperature is accompanied by a red shift in the PL bands across all compositions. In the Ti-doped DHP, a pronounced blue shift at low temperatures is observed, which can be attributed to the involvement of Ti³⁺-related electronic states. An analysis of the activation energy of thermal luminescence quenching and the results of time-resolved spectroscopy revealed the activation of thermal processes in the titanium-containing sample and their rapid decay, whereas replacing titanium with silicon leads to more stable luminescence in the crystal under study. Thus, the enhanced luminescence characteristics of double halide perovskites doped with Ti, Si, and Zr highlight their potential for advanced photonic and optoelectronic applications. Full article

The development of polyolefin from bio-renewables has been considered an important subject in terms of circular economy. In this study, exploring the possibility of β-myrcene (MY) incorporation in propene copolymerization has been studied in the presence of various catalysts: phenoxide-modified half-titanocene, Cp’TiCl₂(O-2,6-ⁱPr₂-4-C₆H₃) [Cp’ = Cp* (C₅Me₅), Me₃SiC₅H₄], and ketimide-modified half-titanicene, Cp’TiCl₂(N=C^tBu₂) (Cp’ = Cp*, Cp). Among the complexes tested, the permethylated Cp* catalysts, Cp*TiCl₂(O-2,6-ⁱPr₂-4-C₆H₃) and Cp*TiCl₂(N=C^tBu₂), exhibited moderate catalytic activities in the copolymerizations, affording the copolymers up to 3 mol% MY incorporation. The other catalysts showed negligible activity in the attempted copolymerizations. The resulting copolymers were amorphous and possessed sole glass transition temperatures (T_g), suggesting uniform compositions; the T_g values decreased with increasing comonomer (MY) content, reaching values as low as −17 °C. The results introduce valuable insights into the structure–property relationships of myrcene-based copolymers and pave the way for the future designs of tailored molecular catalysts for the synthesis of biobased elastomers. Full article

Background: Cardiolipin (CL) is a phospholipid composed of a glycerol linked with two phosphatidate moieties that constitutes an integral part of the human inner mitochondrial membrane under physiological conditions. It is also vital for bacterial membrane transport and key bacterial functions associated with cell division and infection. CL is released in the cytosol or into the extracellular milieu upon cell death and during inflammation. We therefore tested the ability of CL to activate and expand tumor infiltrating lymphocytes (TIL) from patients with epithelial cancer. Methods: TIL were isolated from gastrointestinal tumor tissues and expanded in vitro in the presence of CL. The role of the NLRP3 inflammasome was evaluated using the specific inhibitor MCC950 and siRNA-mediated silencing of NLRP3. Phenotypic changes and T-cell potency were assessed via CXCL9/10 expression levels. To characterize the immune repertoire, deep TCR sequencing was performed to compare the TCR Vα and Vβ CDR3 regions between TIL and the corresponding tumor tissue. Recognition of autologous tumor cells and tumor-specific mutations, including mutations in KRAS and mitochondrial UQCRFS1 (D145V), was assessed using MHC class I and II restriction assays. Results: CL-expanded TIL exhibited increased CXCL9/10 expression, which is associated with increased potency of tissue invasion. CL-TIL exhibited broader recognition of frequently occurring KRAS mutations, and this effect could be blocked with an inhibitor (MCC950) of the NLRP3 pathway, a multiprotein inflammatory complex associated with danger signaling. TIL exhibited an enriched TCR Vα and Vβ CDR3 repertoire compared to tumor tissue, as defined by deep TCR sequencing. TCR αβ+ TIL recognized autologous tumor tissue in an MHC class I– and class II–restricted fashion, including the mutant HLA-DP–restricted mitochondrial protein associated with the electron respiratory chain complex III (UQCRFS1 D145V) presented by autologous tumor cells. Conclusions: CL activates the NLRP3 inflammasome pathway in TIL from patients with GI cancer and increases CXCL9/CXCL10 expression in TIL, resulting in enhanced recognition of mutant cancer–associated target epitopes, including a mitochondrial protein. CL may provide a danger signal: that facilitates TIL expansion via CL-activated pathways. Full article

The hydrogeochemical characterization of shallow volcanic lakes at the Sete Cidades Volcano (São Miguel, Azores) provides new insights into the processes controlling water chemistry in low-depth lacustrine systems within active volcanic environments. Fourteen lakes (0.6–4 m deep) were sampled during two campaigns (winter 2024 and spring/summer 2025), combining in situ physicochemical measurements and major ion analyses along vertical profiles. The lakes are holomictic, cold (11.3–17.6 °C), slightly acidic (pH 5.66–5.95), and weakly mineralized (EC ~65–69 µS/cm), indicating dilute waters of predominantly meteoric origin. Hydrochemical facies are dominated by Na–Cl type, with strong correlations between chloride and conductivity (r = 0.857), supporting a major contribution from marine atmospheric deposition. To move beyond correlation-based interpretation, Gibbs diagrams and saturation indices (PHREEQC) were applied to constrain the dominant geochemical processes. Most samples plot within the precipitation dominance field, while all calculated saturation indices are negative (SI < 0), indicating undersaturation with respect to carbonate, evaporite, and silicate minerals. These results demonstrate that water chemistry is primarily controlled by atmospheric inputs, with only minor contributions from water–rock interaction and negligible influence of evaporation or mineral equilibrium processes. Seasonal increases in HCO₃⁻ and dissolved CO₂ at depth suggest enhanced organic matter decomposition during warmer periods, highlighting the role of biogeochemical processes in modulating carbon dynamics in shallow systems. The absence of a clear hydrothermal signature further distinguishes these lakes from deeper volcanic systems in the Azores. This study provides the first integrated hydrogeochemical framework for shallow volcanic lakes in the region, combining classical hydrochemistry with process-based tools. The results establish a quantitative baseline for assessing environmental change and improve the interpretation of external (atmospheric) versus internal (geochemical and biological) controls in volcanic lake systems. Full article